gpio-amd8111: check ioport_map return value

ioport_map() may fail. Its safe to check the return value.
Signed-off-by: NVarka Bhadram <varkab@cdac.in>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-amd8111.c

@@ -213,6 +213,11 @@ static int __init amd_gpio_init(void)
 		goto out;
 	}
 	gp.pm = ioport_map(gp.pmbase + PMBASE_OFFSET, PMBASE_SIZE);
+	if (!gp.pm) {
+		dev_err(&pdev->dev, "Couldn't map io port into io memory\n");
+		err = -ENOMEM;
+		goto out;
+	}
 	gp.pdev = pdev;
 	gp.chip.dev = &pdev->dev;