[PATCH] mbxfb: Add YUV video overlay support

This patch adds a way to create and use the video plane (YUV overlay) and
scaling video scaling features of the chip.

The overlay is configured, resized and modified using a device specific
ioctl.

Also included in this patch:
  - If no platform data was passed, print an error and exit instead of crashing.
  - Added a write_reg(_dly) macro. This improves readability when
    manipulating chip registers. (no more udelay() after each write).
  - Comments about some issues.

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>