[PATCH] mbxfb: Add more registers bits access macros

This patch adds register bits access macros for chip's Video Plane, Scaling
and interrupt registers.

Signed-off-by: Raphael Assenat <raph@8d.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Acked-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>