sde-drm: Add support to quad split.

  - Split layer into two parts such that they get staged
    on left and right panels.
  - RM further programs each layer to left and right pipes
    if it exceeds clock requirements.
  - Source split is supported on left and right mixer pairs
    exclusively.
  - Part of fix from change-id I15dc98f is included.

Change-Id: I15552f94fc4f239408e8aebc60cdba322e2212df
CRs-fixed: 2423335
5 files changed