drm/atomic: integrate modeset lock with private objects

Follow the same pattern of locking as with other state objects. This
avoids boilerplate in the driver.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20181022123122.30468-1-boris.brezillon@bootlin.com

drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c

@@ -144,7 +144,7 @@ static int mdp5_global_obj_init(struct mdp5_kms *mdp5_kms)
 
 	state->mdp5_kms = mdp5_kms;
 
-	drm_atomic_private_obj_init(&mdp5_kms->glob_state,
+	drm_atomic_private_obj_init(mdp5_kms->dev, &mdp5_kms->glob_state,
 				    &state->base,
 				    &mdp5_global_state_funcs);
 	return 0;