pinctrl: sppctl: use gpiochip_dup_line_label()

Use the new gpiochip_dup_line_label() helper to safely retrieve the
descriptor label.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/sunplus/sppctl.c

@@ -4,6 +4,7 @@
  * Copyright (C) Sunplus Tech / Tibbo Tech.
  */
 
+#include <linux/cleanup.h>
 #include <linux/bitfield.h>
 #include <linux/device.h>
 #include <linux/err.h>
@@ -500,16 +501,15 @@ static int sppctl_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
 
 static void sppctl_gpio_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
-	const char *label;
 	int i;
 
 	for (i = 0; i < chip->ngpio; i++) {
-		label = gpiochip_is_requested(chip, i);
-		if (!label)
-			label = "";
+		char *label __free(kfree) = gpiochip_dup_line_label(chip, i);
+		if (IS_ERR(label))
+			continue;
 
 		seq_printf(s, " gpio-%03d (%-16.16s | %-16.16s)", i + chip->base,
-			   chip->names[i], label);
+			   chip->names[i], label ?: "");
 		seq_printf(s, " %c", sppctl_gpio_get_direction(chip, i) ? 'I' : 'O');
 		seq_printf(s, ":%d", sppctl_gpio_get(chip, i));
 		seq_printf(s, " %s", sppctl_first_get(chip, i) ? "gpi" : "mux");