gpio: set device type for GPIO chips

It's useful to have the device type information for those sub-devices
that are actually GPIO chips registered with GPIOLIB. While at it: use
the device type struct to setup the release callback which is the
preferred way to use the device API.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpio/gpiolib.c

@@ -663,6 +663,11 @@ static void gpiodev_release(struct device *dev)
 	kfree(gdev);
 }
 
+static const struct device_type gpio_dev_type = {
+	.name = "gpio_chip",
+	.release = gpiodev_release,
+};
+
 #ifdef CONFIG_GPIO_CDEV
 #define gcdev_register(gdev, devt)	gpiolib_cdev_register((gdev), (devt))
 #define gcdev_unregister(gdev)		gpiolib_cdev_unregister((gdev))
@@ -680,6 +685,8 @@ static int gpiochip_setup_dev(struct gpio_device *gdev)
 	struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
 	int ret;
 
+	device_initialize(&gdev->dev);
+
 	/*
 	 * If fwnode doesn't belong to another device, it's safe to clear its
 	 * initialized flag.
@@ -691,9 +698,6 @@ static int gpiochip_setup_dev(struct gpio_device *gdev)
 	if (ret)
 		return ret;
 
-	/* From this point, the .release() function cleans up gpio_device */
-	gdev->dev.release = gpiodev_release;
-
 	ret = gpiochip_sysfs_register(gdev);
 	if (ret)
 		goto err_remove_device;
@@ -825,6 +829,8 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
 	if (!gdev)
 		return -ENOMEM;
+
+	gdev->dev.type = &gpio_dev_type;
 	gdev->dev.bus = &gpio_bus_type;
 	gdev->dev.parent = gc->parent;
 	gdev->chip = gc;
@@ -851,7 +857,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	if (ret)
 		goto err_free_ida;
 
-	device_initialize(&gdev->dev);
 	if (gc->parent && gc->parent->driver)
 		gdev->owner = gc->parent->driver->owner;
 	else if (gc->owner)