gbefb: cmap FIFO timeout

Writes to the cmap fifo while the display is blanked caused cmap FIFO
timeout messages and a wrong colormap.  To avoid this the driver now
maintains a colormap in memory and updates the colormap after the display
is unblanked.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>