gpio: altera: use of_mm_gpiochip_remove() to fix memory leak

This driver calls of_mm_gpiochip_add() to add a memory mapped gpio
chip.  So, of_mm_gpiochip_remove() should be used when removing it.

The direct call of gpiochip_remove() misses unmapping the register
and freeing the label.
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>

drivers/gpio/gpio-altera.c

@@ -338,7 +338,7 @@ static int altera_gpio_remove(struct platform_device *pdev)
 {
 	struct altera_gpio_chip *altera_gc = platform_get_drvdata(pdev);
 
-	gpiochip_remove(&altera_gc->mmchip.gc);
+	of_mm_gpiochip_remove(&altera_gc->mmchip);
 
 	return 0;
 }