pinctrl: renesas: rza2: Fix potential NULL pointer dereference

`chip.label` in rza2_gpio_register() could be NULL.
Add the missing check.

Signed-off-by: Chenyuan Yang <chenyuan0y@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Link: https://lore.kernel.org/20250210232552.1545887-1-chenyuan0y@gmail.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/pinctrl/renesas/pinctrl-rza2.c

@@ -246,6 +246,9 @@ static int rza2_gpio_register(struct rza2_pinctrl_priv *priv)
 	int ret;
 
 	chip.label = devm_kasprintf(priv->dev, GFP_KERNEL, "%pOFn", np);
+	if (!chip.label)
+		return -ENOMEM;
+
 	chip.parent = priv->dev;
 	chip.ngpio = priv->npins;