gpio: ftgpio010: Fix platform_get_irq's error checking

The platform_get_irq() function returns negative if an error occurs.
zero or positive number on success. platform_get_irq() error checking
for zero is not correct.
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-ftgpio010.c

@@ -176,8 +176,8 @@ static int ftgpio_gpio_probe(struct platform_device *pdev)
 		return PTR_ERR(g->base);
 
 	irq = platform_get_irq(pdev, 0);
-	if (!irq)
-		return -EINVAL;
+	if (irq <= 0)
+		return irq ? irq : -EINVAL;
 
 	ret = bgpio_init(&g->gc, dev, 4,
 			 g->base + GPIO_DATA_IN,