drm/msm/sde: Expose the HDR support capability of the chipset

Expose HDR capability using a property to the userspace.

This will help userspace to decide whether to invoke the HDR library
and pass the relevant parameters to be sent to the sink.

Change-Id: I3c4bf4d6c4e0f0babdf49b3c99baab42dcb2b5c0
Signed-off-by: Srikanth Rajagopalan <rasrik@codeaurora.org>