drm/vc4: Use for_each_plane_in_state

We want to hide drm_atomic_stat internals a bit better.

Cc: Eric Anholt <eric@anholt.net>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464818821-5736-6-git-send-email-daniel.vetter@ffwll.ch

drivers/gpu/drm/vc4/vc4_kms.c

@@ -111,6 +111,8 @@ static int vc4_atomic_commit(struct drm_device *dev,
 	int i;
 	uint64_t wait_seqno = 0;
 	struct vc4_commit *c;
+	struct drm_plane *plane;
+	struct drm_plane_state *new_state;
 
 	c = commit_init(state);
 	if (!c)
@@ -130,13 +132,7 @@ static int vc4_atomic_commit(struct drm_device *dev,
 		return ret;
 	}
 
-	for (i = 0; i < dev->mode_config.num_total_plane; i++) {
-		struct drm_plane *plane = state->planes[i];
-		struct drm_plane_state *new_state = state->plane_states[i];
-
-		if (!plane)
-			continue;
-
+	for_each_plane_in_state(state, plane, new_state, i) {
 		if ((plane->state->fb != new_state->fb) && new_state->fb) {
 			struct drm_gem_cma_object *cma_bo =
 				drm_fb_cma_get_gem_obj(new_state->fb, 0);