gpio: altera: fix return value of altera_gpio_remove()

The remove callback never succeeds, which seems odd.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NAlexandre Courbot <acourbot@nvidia.com>
Acked-by: NTien Hock Loh <thloh@altera.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-altera.c

@@ -340,7 +340,7 @@ static int altera_gpio_remove(struct platform_device *pdev)
 
 	gpiochip_remove(&altera_gc->mmchip.gc);
 
-	return -EIO;
+	return 0;
 }
 
 static const struct of_device_id altera_gpio_of_match[] = {