drm: Fix references to drm_plane_helper_check_state()

As of commit a01cb8ba ("drm: Move drm_plane_helper_check_state()
into drm_atomic_helper.c"), drm_plane_helper_check_state() no longer
exists, but is part of drm_atomic_helper_check_plane_state().
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/8bb42a92fc20e3d11e5847e7f15a47c687b73104.1689779916.git.geert+renesas@glider.be

drivers/gpu/drm/renesas/rcar-du/rcar_du_plane.c

@@ -600,7 +600,8 @@ int __rcar_du_plane_atomic_check(struct drm_plane *plane,
 	if (!state->crtc) {
 		/*
 		 * The visible field is not reset by the DRM core but only
-		 * updated by drm_plane_helper_check_state(), set it manually.
+		 * updated by drm_atomic_helper_check_plane_state(), set it
+		 * manually.
 		 */
 		state->visible = false;
 		*format = NULL;

drivers/gpu/drm/tidss/tidss_plane.c

@@ -38,7 +38,8 @@ static int tidss_plane_atomic_check(struct drm_plane *plane,
 	if (!new_plane_state->crtc) {
 		/*
 		 * The visible field is not reset by the DRM core but only
-		 * updated by drm_plane_helper_check_state(), set it manually.
+		 * updated by drm_atomic_helper_check_plane_state(), set it
+		 * manually.
 		 */
 		new_plane_state->visible = false;
 		return 0;