fbdev: move arch-specific bits to their respective subdirectories

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: Antonino Daplas <adaplas@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>