gpu: drm: use for_each_endpoint_of_node()

We already have for_each_endpoint_of_node(), don't use
of_graph_get_next_endpoint() directly. Replace it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/87jzh3lnts.wl-kuninori.morimoto.gx@renesas.com

Author: morimoto

drivers/gpu/drm/omapdrm/dss/base.c

@@ -242,8 +242,7 @@ static void omapdss_walk_device(struct device *dev, struct device_node *node,
 
 	of_node_put(n);
 
-	n = NULL;
-	while ((n = of_graph_get_next_endpoint(node, n)) != NULL) {
+	for_each_endpoint_of_node(node, n) {
 		struct device_node *pn = of_graph_get_remote_port_parent(n);
 
 		if (!pn)