pinctrl: iproc: allow for error from platform_get_irq()

platform_get_irq() can return an error code. Allow for this when getting
the irq.

Fixes: 6f265e5d4d ("pinctrl: bcm-iproc: Pass irqchip when adding gpiochip")
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20191003000310.17099-2-chris.packham@alliedtelesis.co.nz
Acked-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/bcm/pinctrl-iproc-gpio.c

@@ -845,7 +845,7 @@ static int iproc_gpio_probe(struct platform_device *pdev)
 
 	/* optional GPIO interrupt support */
 	irq = platform_get_irq(pdev, 0);
-	if (irq) {
+	if (irq > 0) {
 		struct irq_chip *irqc;
 		struct gpio_irq_chip *girq;