gpio: stmpe: 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/gpio/gpio-stmpe.c

@@ -5,6 +5,7 @@
  * Author: Rabin Vincent <rabin.vincent@stericsson.com> for ST-Ericsson
  */
 
+#include <linux/cleanup.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -255,14 +256,17 @@ static void stmpe_dbg_show_one(struct seq_file *s,
 {
 	struct stmpe_gpio *stmpe_gpio = gpiochip_get_data(gc);
 	struct stmpe *stmpe = stmpe_gpio->stmpe;
-	const char *label = gpiochip_is_requested(gc, offset);
 	bool val = !!stmpe_gpio_get(gc, offset);
 	u8 bank = offset / 8;
 	u8 dir_reg = stmpe->regs[STMPE_IDX_GPDR_LSB + bank];
 	u8 mask = BIT(offset % 8);
 	int ret;
 	u8 dir;
 
+	char *label __free(kfree) = gpiochip_dup_line_label(gc, offset);
+	if (IS_ERR(label))
+		return;
+
 	ret = stmpe_reg_read(stmpe, dir_reg);
 	if (ret < 0)
 		return;