pinctrl: wpcm450: Correct the fwnode_irq_get() return value check

fwnode_irq_get() can return zero to indicate IRQ mapping errors.
Handle this case by skipping the interrupt resource.

Fixes: a1d1e0e ("pinctrl: nuvoton: Add driver for WPCM450")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20220927175509.15695-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/nuvoton/pinctrl-wpcm450.c

@@ -1081,10 +1081,13 @@ static int wpcm450_gpio_register(struct platform_device *pdev,
 
 		girq->num_parents = 0;
 		for (i = 0; i < WPCM450_NUM_GPIO_IRQS; i++) {
-			int irq = fwnode_irq_get(child, i);
+			int irq;
 
+			irq = fwnode_irq_get(child, i);
 			if (irq < 0)
 				break;
+			if (!irq)
+				continue;
 
 			girq->parents[i] = irq;
 			girq->num_parents++;