OMAPDSS: DISPC: VIDEO3 pipeline support

Add support for VIDEO3 pipeline on OMAP4:
- Add VIDEO3 pipeline information in dss_features and omapdss.h
- Add VIDEO3 pipeline register coefficients in dispc.h
- Create a new overlay structure corresponding to VIDEO3.
- Make changes in dispc.c for VIDEO3

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>