gpio: iop: fix devm_ioremap_resource() return value checking

devm_ioremap_resource() returns a pointer to the remapped memory or
an ERR_PTR() encoded error code on failure.  Fix the check inside
iop3xx_gpio_probe() accordingly.

Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-iop.c

@@ -111,6 +111,8 @@ static int iop3xx_gpio_probe(struct platform_device *pdev)
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
 
 	return gpiochip_add(&iop3xx_chip);
 }