drm/komeda: Add komeda_plane/plane_helper_funcs

Per komeda design KMS-plane maps to komeda layer input pipeline.
komeda_plane_atomic_check is for building a komeda layer input pipeline.

And KMS-plane is only a user of komeda resources. so there is no real HW
update for plane, but all HW update will be handled in crtc->flush.

v2: Rebase

Signed-off-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>