drm/plane: Pass old state to ->atomic_update()

In most situations it will be useful to have the old state passed to the
->atomic_update() callback. For example if a plane is being disabled the
new state's .crtc field will be NULL, but some drivers may rely on this
field to program the CRTCs registers.

v2: rename variable to old_plane_state and remove redundant comment as
suggested by Daniel Vetter, remove an Exynos hunk that doesn't apply to
drm-next and add a hunk for pending MSM mdp5 changes

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/msm/mdp/mdp4/mdp4_plane.c

@@ -107,7 +107,8 @@ static int mdp4_plane_atomic_check(struct drm_plane *plane,
 	return 0;
 }
 
-static void mdp4_plane_atomic_update(struct drm_plane *plane)
+static void mdp4_plane_atomic_update(struct drm_plane *plane,
+				     struct drm_plane_state *old_state)
 {
 	struct drm_plane_state *state = plane->state;
 	int ret;

drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c

@@ -213,7 +213,8 @@ static int mdp5_plane_atomic_check(struct drm_plane *plane,
 	return 0;
 }
 
-static void mdp5_plane_atomic_update(struct drm_plane *plane)
+static void mdp5_plane_atomic_update(struct drm_plane *plane,
+				     struct drm_plane_state *old_state)
 {
 	struct mdp5_plane *mdp5_plane = to_mdp5_plane(plane);
 	struct drm_plane_state *state = plane->state;