drm/cirrus: add missing drm_helper_force_disable_all() call.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20190401140306.28063-4-kraxel@redhat.com

drivers/gpu/drm/cirrus/cirrus_mode.c

@@ -615,6 +615,7 @@ void cirrus_modeset_fini(struct cirrus_device *cdev)
 	cirrus_fbdev_fini(cdev);
 
 	if (cdev->mode_info.mode_config_initialized) {
+		drm_helper_force_disable_all(cdev->dev);
 		drm_mode_config_cleanup(cdev->dev);
 		cdev->mode_info.mode_config_initialized = false;
 	}