macfb: cleanup

Cleanup whitespace and code style. Remove unused #includes and prototypes.
Remove obsolete, redundant or misleading comments. Remove dead code and
redundant initialisers.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>