pinctrl-st: fix of_irq_to_resource() result check

of_irq_to_resource() has recently been fixed to return negative error #'s
along with 0 in case of failure, however the ST driver still only regards
0 as failure indication -- fix it up.

Fixes: 7a4228bb ("of: irq: use of_irq_get() in of_irq_to_resource()")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-st.c

@@ -1521,7 +1521,7 @@ static int st_gpiolib_register_bank(struct st_pinctrl *info,
 	 *	[irqN]----> [gpio-bank (n)]
 	 */
 
-	if (of_irq_to_resource(np, 0, &irq_res)) {
+	if (of_irq_to_resource(np, 0, &irq_res) > 0) {
 		gpio_irq = irq_res.start;
 		gpiochip_set_chained_irqchip(&bank->gpio_chip, &st_gpio_irqchip,
 					     gpio_irq, st_gpio_irq_handler);