OMAP: move arch/arm/plat-omap/include/plat/vrfb.h

Now that vrfb driver is not omap dependent anymore, we can move vrfb.h
from arch/arm/plat-omap/include/plat to include/video/omapvrfb.h.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Vaibhav Hiremath <hvaibhav@ti.com>