OMAP4: DSS2: HDMI: HDMI panel driver addition in the DSS

The panel driver(hdmi_omap4_panel.c) in omap2/dss acts as a controller
to manage the enable and disable requests and synchronize audio and video.

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