gpio: mt7621: report failure of devm_kasprintf()

kasprintf() may return NULL on failure of internal allocation thus the
assigned  label  is not safe if not explicitly checked. On error
mediatek_gpio_bank_probe() returns negative values so -ENOMEM in the
(unlikely) failure case should be fine here.

Fixes: 4ba9c3af ("gpio: mt7621: Add a driver for MT7621")
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Sean Wang <sean.wang@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mt7621.c

@@ -244,6 +244,8 @@ mediatek_gpio_bank_probe(struct device *dev,
 	rg->chip.of_xlate = mediatek_gpio_xlate;
 	rg->chip.label = devm_kasprintf(dev, GFP_KERNEL, "%s-bank%d",
 					dev_name(dev), bank);
+	if (!rg->chip.label)
+		return -ENOMEM;
 
 	ret = devm_gpiochip_add_data(dev, &rg->chip, mtk);
 	if (ret < 0) {