drm/msm/dp: decouple static and dynamic HDR metadata

Move the static metadata packets to an available generic SDP and
reserve the VSC extension SDP for dynamic metadata packets. The
payload for dynamic metadata comes from MEMPOOL and would
otherwise overwrite the static metadata payload. This change
ensures that both these distinct metadata packets are sent
correctly for every applicable frame.

Change-Id: Ifeb2e975ff9e7a1ce024fbdf5e72fa5422e9e709
Signed-off-by: Steve Cohen <cohens@codeaurora.org>