In preparation for atomic conversion, let's use the transitional atomic
helpers drm_plane_helper_update/disable.
Signed-off-by: NGabriel Krisman Bertazi <krisman@collabora.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170227204328.18761-6-krisman@collabora.co.ukSigned-off-by: NGerd Hoffmann <kraxel@redhat.com>