ASoC: audio-graph-card2: Use helper function of_get_child_count()

of_get_child_count() can help to get the num of child directly and we
don't need to manually count the child num. No functional change with
this conversion.
Signed-off-by: Zhang Zekun <zhangzekun11@huawei.com>
Reviewed-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20240827070650.11424-3-zhangzekun11@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/generic/audio-graph-card2.c

@@ -1141,21 +1141,12 @@ static int graph_counter(struct device_node *lnk)
 	 */
 	if (graph_lnk_is_multi(lnk)) {
 		struct device_node *ports = port_to_ports(lnk);
-		struct device_node *port = NULL;
-		int cnt = 0;
 
 		/*
 		 * CPU/Codec = N:M case has many endpoints.
 		 * We can't use of_graph_get_endpoint_count() here
 		 */
-		while(1) {
-			port = of_get_next_child(ports, port);
-			if (!port)
-				break;
-			cnt++;
-		}
-
-		return cnt - 1;
+		return of_get_child_count(ports) - 1;
 	}
 	/*
 	 * Single CPU / Codec