Move arch-specific bits of fb_mmap() to their respective subdirectories

[bob.picco@hp.com: efi_range_is_wc is referenced but not declared]
[bunk@stusta.de: fix include/asm-m68k/fb.h]
Signed-off-by: NAntonino Daplas <adaplas@gmail.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>