OMAP4: DSS2: HDMI: Move HDMI IP independent generic header

Some of the header file definitions that are there in the hdmi.h are generic
and can be used across OMAP's, Thus moving generic definition to new file.

Signed-off-by: Mythri P K <mythripk@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>