drm/exynos/ipp: cancel works before command node clean

All pending works should be canceled prior to its removal.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_ipp.c

@@ -502,6 +502,11 @@ err_clear:
 static void ipp_clean_cmd_node(struct ipp_context *ctx,
 				struct drm_exynos_ipp_cmd_node *c_node)
 {
+	/* cancel works */
+	cancel_work_sync(&c_node->start_work->work);
+	cancel_work_sync(&c_node->stop_work->work);
+	cancel_work_sync(&c_node->event_work->work);
+
 	/* delete list */
 	list_del(&c_node->list);