fbdev: clean the penguin's dirty feet

When booting in a direct color mode, the penguin has dirty feet, i.e.,
some pixels have the wrong color.  This is caused by
fb_set_logo_directpalette() which does not initialize the last 32 palette
entries.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>