gpio: 74x164: 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().

Cc: Alexander Shiyan <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-74x164.c

···
 	u8			buffer[0];
 };
 
-static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
-{
-	return container_of(gc, struct gen_74x164_chip, gpio_chip);
-}
-
 static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
 {
 	struct spi_transfer xfer = {
···
 
 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
 {
-	struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
+	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
 	u8 bank = chip->registers - 1 - offset / 8;
 	u8 pin = offset % 8;
 	int ret;
···
 static void gen_74x164_set_value(struct gpio_chip *gc,
 		unsigned offset, int val)
 {
-	struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
+	struct gen_74x164_chip *chip = gpiochip_get_data(gc);
 	u8 bank = chip->registers - 1 - offset / 8;
 	u8 pin = offset % 8;
 
···
 		goto exit_destroy;
 	}
 
-	ret = gpiochip_add(&chip->gpio_chip);
+	ret = gpiochip_add_data(&chip->gpio_chip, chip);
 	if (!ret)
 		return 0;