drm/msm: add sink capabilities for HDR support

Populate HDR sink capabilities to a DRM blob.

These capabilities shall be used by the userspace
to calculate the sink HDR properties and setting them.

Change-Id: I7c2dbca375c456052ad73889b011553090bcf8f1
Signed-off-by: Srikanth Rajagopalan <rasrik@codeaurora.org>