gpio: altera: fix return value of altera_gpio_remove()

The remove callback never succeeds, which seems odd.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Tien Hock Loh <thloh@altera.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-altera.c b/drivers/gpio/gpio-altera.c
index 0f3d336..675d15d 100644
--- a/drivers/gpio/gpio-altera.c
+++ b/drivers/gpio/gpio-altera.c
@@ -340,7 +340,7 @@
 
 	gpiochip_remove(&altera_gc->mmchip.gc);
 
-	return -EIO;
+	return 0;
 }
 
 static const struct of_device_id altera_gpio_of_match[] = {