net: renesas: rswitch: Convert to for_each_available_child_of_node()

Simplify rswitch_get_port_node() by using the
for_each_available_child_of_node() helper instead of manually ignoring
unavailable child nodes, and leaking a reference.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/54f544d573a64b96e01fd00d3481b10806f4d110.1738771798.git.geert+renesas@glider.be
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/renesas/rswitch.c

@@ -1287,17 +1287,14 @@ static struct device_node *rswitch_get_port_node(struct rswitch_device *rdev)
 	if (!ports)
 		return NULL;
 
-	for_each_child_of_node(ports, port) {
+	for_each_available_child_of_node(ports, port) {
 		err = of_property_read_u32(port, "reg", &index);
 		if (err < 0) {
 			port = NULL;
 			goto out;
 		}
-		if (index == rdev->etha->index) {
-			if (!of_device_is_available(port))
-				port = NULL;
+		if (index == rdev->etha->index)
 			break;
-		}
 	}
 
 out: