drm/msm: add RGB 30-bit deep color support

Check if the TV supports deep color and adjust the
pxl clock accordingly before setting the mode. Also
make sure that this pxl clock is within the limits
of the sink.

Change-Id: I3c44c06ea54b6c49e19c8c41d693000f7c3feeb7
Signed-off-by: Yuan Zhao <yzhao@codeaurora.org>
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>
Signed-off-by: Chirag Khurana <ckhurana@codeaurora.org>