video: s3c_fb.c: fix build with CONFIG_HOTPLUG=n

Fixes `s3c_fb_remove' referenced in section `.data' of
drivers/built-in.o: defined in discarded section `.devexit.text' of
drivers/built-in.o

With CONFIG_HOTPLUG=n, functions marked with __devexit gets removed,
so make sure we use __devexit_p when referencing pointers to them.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>