gpio-sta2x11: Fix potential NULL pointer dereference

devm_kzalloc can return NULL. Check for it before dereferencing.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-sta2x11.c

@@ -371,6 +371,8 @@ static int gsta_probe(struct platform_device *dev)
 	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 
 	chip = devm_kzalloc(&dev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
 	chip->dev = &dev->dev;
 	chip->reg_base = devm_request_and_ioremap(&dev->dev, res);