OMAP: OMAPFB: split omapfb.h

Split arch/arm/plat-omap/include/mach/omapfb.h into two files:

include/linux/omapfb.h - ioctls etc for userspace and some kernel
                         stuff for board files
drivers/video/omap/omapfb.h - for omapfb internal use

This cleans up omapfb.h and also makes it easier for the upcoming new
DSS driver to co-exist with the old driver.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>