Revert "fbdev: atafb - add palette register check"

This reverts commit 8546e3ce, as it's a
partial duplicate of commit 2f390380
("fbdev: add palette register check to several drivers").

The former went in first through the m68k tree, the latter through Andrew
Morton.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>