drm/sun4i: tv: Check mode pointer

The drm_mode_create call might return NULL in case of a failure, and the
current code doesn't check for that. Make sure it does.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

drivers/gpu/drm/sun4i/sun4i_tv.c

@@ -507,9 +507,15 @@ static int sun4i_tv_comp_get_modes(struct drm_connector *connector)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(tv_modes); i++) {
-		struct drm_display_mode *mode = drm_mode_create(connector->dev);
+		struct drm_display_mode *mode;
 		const struct tv_mode *tv_mode = &tv_modes[i];
 
+		mode = drm_mode_create(connector->dev);
+		if (!mode) {
+			DRM_ERROR("Failed to create a new display mode\n");
+			return 0;
+		}
+
 		strcpy(mode->name, tv_mode->name);
 
 		sun4i_tv_mode_to_drm_mode(tv_mode, mode);