Use bitrev8 for nvidiafb, rivafb, and tgafb drivers

Cc: Antonino Daplas <adaplas@pol.net>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>