Our .update_plane() handlers do the same check/prepare/commit/cleanup
steps regardless of plane type. Consolidate them all into a single
function that calls check/commit through a vtable.
Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Reviewed-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>