ARM: OMAP2+: Fix missing inline functions for Makefile cleanup

Commit f41caddb

 (omap2+: Use
Kconfig symbol in Makefile instead of obj-y) cleaned up the
omap2+ Makefile. However this did not account for the inline
functions that are now needed for board_flash_init and
board_nand_init.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>