of: property: use unsigned int return on of_graph_get_endpoint_count()

Because of of_graph_get_endpoint_count() doesn't report error,
just return count of endpoint, the return type should be unsigned.
Tidyup it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/87plxbcvzb.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Rob Herring <robh@kernel.org>

drivers/of/property.c

@@ -818,10 +818,10 @@ EXPORT_SYMBOL(of_graph_get_remote_port);
  *
  * Return: count of endpoint of this device node
  */
-int of_graph_get_endpoint_count(const struct device_node *np)
+unsigned int of_graph_get_endpoint_count(const struct device_node *np)
 {
 	struct device_node *endpoint;
-	int num = 0;
+	unsigned int num = 0;
 
 	for_each_endpoint_of_node(np, endpoint)
 		num++;

include/linux/of_graph.h

@@ -41,7 +41,7 @@ struct of_endpoint {
 bool of_graph_is_present(const struct device_node *node);
 int of_graph_parse_endpoint(const struct device_node *node,
 				struct of_endpoint *endpoint);
-int of_graph_get_endpoint_count(const struct device_node *np);
+unsigned int of_graph_get_endpoint_count(const struct device_node *np);
 struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id);
 struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 					struct device_node *previous);
@@ -68,7 +68,7 @@ static inline int of_graph_parse_endpoint(const struct device_node *node,
 	return -ENOSYS;
 }
 
-static inline int of_graph_get_endpoint_count(const struct device_node *np)
+static inline unsigned int of_graph_get_endpoint_count(const struct device_node *np)
 {
 	return 0;
 }