Nouveau had a few direct calls to ->disable_plane, I replaced those
with drm_plane_force_disable. Same story for shmob.

Otherwise no code changes.

Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170322215058.8671-5-daniel.vetter@ffwll.ch