Fix -Wstringop-truncation warnings

Fixes the following warnings:
In function 'strncpy',
    inlined from 'spi_boards_scan' at spi_boards.c:203:9:
/usr/include/bits/string_fortified.h:106:10: warning: '__builtin_strncpy'
output truncated before terminating nul copying 4 bytes
from a string of the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));

In file included from /usr/include/string.h:495,
                 from pci_boards.c:34:
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1281:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1240:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1205:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1177:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1144:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1117:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1089:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1056:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:1026:21:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:995:17:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:967:17:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:940:17:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:912:17:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:885:17:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘pci_boards_scan’ at pci_boards.c:851:17:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 14 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In file included from /usr/include/string.h:495,
                 from usb_boards.c:21:
In function ‘strncpy’,
    inlined from ‘usb_boards_scan’ at usb_boards.c:188:9:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘usb_boards_scan’ at usb_boards.c:147:13:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
output truncated before terminating nul copying 4 bytes from a string of
the same length [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:329:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:306:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:283:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:259:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:235:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:211:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:186:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function ‘strncpy’,
    inlined from ‘eth_scan_one_addr’ at eth_boards.c:161:13,
    inlined from ‘eth_scan_one_addr.isra.0’ at eth_boards.c:136:12:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output
may be truncated copying 16 bytes from a string of length 19 [-Wstringop-truncation]
  106 |   return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Damian Wrobel <dwrobel@ertelnet.rybnik.pl>