gpio: mc33880: use gpiochip data pointer

This makes the driver use the data pointer added to the gpio_chip
to store a pointer to the state container instead of relying on
container_of().

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-mc33880.c b/drivers/gpio/gpio-mc33880.c
index b46b9e5..0f0df79 100644
--- a/drivers/gpio/gpio-mc33880.c
+++ b/drivers/gpio/gpio-mc33880.c
@@ -71,7 +71,7 @@
 
 static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
 {
-	struct mc33880 *mc = container_of(chip, struct mc33880, chip);
+	struct mc33880 *mc = gpiochip_get_data(chip);
 
 	mutex_lock(&mc->lock);
 
@@ -135,7 +135,7 @@
 		goto exit_destroy;
 	}
 
-	ret = gpiochip_add(&mc->chip);
+	ret = gpiochip_add_data(&mc->chip, mc);
 	if (ret)
 		goto exit_destroy;