video/macfb: Always initialize DAFB colour table pointer register

Don't skip the framebuffer CLUT pointer register initialization when
the first dafb_setpalette() invocation has regno equal to zero.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>