mtd: onenand: Fix unaligned access

mtd: onenand: Fix unaligned access

Fix unaligned access in OneNAND core. The problem is that the ffchars[] array
is an array of "unsigned char", but in onenand_write_ops_nolock() can be passed
to the memcpy_16() function. The memcpy_16() function will treat the buffer as
an array of "unsigned short", thus triggering unaligned access if the compiler
decided ffchars[] to be not aligned.

I managed to trigger the problem with regular ELDK 5.4 GCC compiler.

Signed-off-by: Marek Vasut <[email protected]>
Cc: Albert Aribaud <[email protected]>
Cc: Scott Wood <[email protected]>
Cc: Tom Rini <[email protected]>