msm: mdss: expose HDR information to panel sys node

Expose HDMI sink HDR information using panel sys node. These
HDR information contains peak brightness and blackness level.

CRs-Fixed: 1113352
Change-Id: Id254ce870184500962d386fd901bf2ab8ec3ee7c
Signed-off-by: Ray Zhang <rayz@codeaurora.org>
Signed-off-by: Lei Chen <chenl@codeaurora.org>