[PATCH] Gigaset ISDN driver error handling fixes

Fix several flaws in the error handling of the Siemens Gigaset ISDN driver,
including one that would cause an Oops when connecting more than one device
of the same type.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>