drm_hwcomposer: Use Planner interface to provision planes

Use the new Planner interface to handle the layer->plane mapping.
This allows us to simplify the Plan() function by offloading the
plane provisioning to the platform specific code.

TEST=Tested on ryu with a variety of window layouts/workloads

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Change-Id: I75a0c5d87a9096e7a83ecbc848c75fee42ee1131
7 files changed