drm/qxl: release shadow on shutdown

In case we have a shadow surface on shutdown release
it so it doesn't leak.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20210204145712.1531203-6-kraxel@redhat.com

drivers/gpu/drm/qxl/qxl_display.c

@@ -1229,5 +1229,9 @@ int qxl_modeset_init(struct qxl_device *qdev)
 
 void qxl_modeset_fini(struct qxl_device *qdev)
 {
+	if (qdev->dumb_shadow_bo) {
+		drm_gem_object_put(&qdev->dumb_shadow_bo->tbo.base);
+		qdev->dumb_shadow_bo = NULL;
+	}
 	qxl_destroy_monitors_object(qdev);
 }