gpio: nomadik: Add missing IS_ERR() check

The function gpio_device_get_desc() can return an error pointer and is
not checked for one. Add check for error pointer.

Fixes: ddeb66d2cb ("gpio: nomadik: don't print out global GPIO numbers in debugfs callbacks")
Cc: stable@vger.kernel.org
Signed-off-by: Ethan Tidmore <ethantidmore06@gmail.com>
Link: https://patch.msgid.link/20260214044531.43539-1-ethantidmore06@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

drivers/gpio/gpio-nomadik.c

@@ -430,6 +430,9 @@ void nmk_gpio_dbg_show_one(struct seq_file *s, struct pinctrl_dev *pctldev,
 #ifdef CONFIG_PINCTRL_NOMADIK
 	if (mode == NMK_GPIO_ALT_C && pctldev) {
 		desc = gpio_device_get_desc(chip->gpiodev, offset);
+		if (IS_ERR(desc))
+			return;
+
 		mode = nmk_prcm_gpiocr_get_mode(pctldev, desc_to_gpio(desc));
 	}
 #endif