msm: mdss: hdmi: add deep color support

Get deep color support information from sink's EDID (Extended Data
Identification Data). Enable deep color output in hdmi transmitter
if the sink supports RGB 30bpp output format.

CRs-Fixed: 1022772
Change-Id: If65ac051253b4e51f6af5cd60f98eaf908b3bcfd
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>