hwc: bring back fb support for primary for mdp3.

mdp3 devices don't support Overlay display commit so currently all mdp303 devices need this.

Change-Id: I98cf0fdae6b9b1100c97ac319ab1c321f55fe507
display: Conditionally restore genlock support

 * Enable genlock support with QCOM_BSP_WITH_GENLOCK.
 * Some blobs need both genlock and metadata.

Change-Id: Idd1df589516534a683e0fa1ef0cfbb7f0e411f67