pinctrl: renesas: rza1: Replace custom code by gpiochip_node_count() call

Since we have generic function to count GPIO controller nodes
under a given device, there is no need to open code it. Replace
custom code by gpiochip_node_count() call.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/pinctrl/renesas/pinctrl-rza1.c

@@ -1154,21 +1154,6 @@ static const struct pinmux_ops rza1_pinmux_ops = {
  * RZ/A1 pin controller driver operations
  */
 
-static unsigned int rza1_count_gpio_chips(struct device_node *np)
-{
-	struct device_node *child;
-	unsigned int count = 0;
-
-	for_each_child_of_node(np, child) {
-		if (!of_property_read_bool(child, "gpio-controller"))
-			continue;
-
-		count++;
-	}
-
-	return count;
-}
-
 /**
  * rza1_parse_gpiochip() - parse and register a gpio chip and pin range
  *
@@ -1255,7 +1240,7 @@ static int rza1_gpio_register(struct rza1_pinctrl *rza1_pctl)
 	unsigned int i;
 	int ret;
 
-	ngpiochips = rza1_count_gpio_chips(np);
+	ngpiochips = gpiochip_node_count(rza1_pctl->dev);
 	if (ngpiochips == 0) {
 		dev_dbg(rza1_pctl->dev, "No gpiochip registered\n");
 		return 0;