drm_hwcomposer: Add rcar-du display backend

ABGR8888 pixel format and layer scaling are unsupported for rcar-du
KMS DRI card. Handle it by overriding the IsClientLayer method for
additional checks.

Signed-off-by: Matvii Zorin <matvii.zorin@globallogic.com>
1 job for backend-validation in 44 seconds (queued for 1 second)