leds: ss4200: fix attribute-creation race

Use the attribute groups of the led-class to create the blink attribute
during probe in order to avoid racing with userspace.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/leds-ss4200.c

@@ -469,6 +469,12 @@ static ssize_t nas_led_blink_store(struct device *dev,
 
 static DEVICE_ATTR(blink, 0644, nas_led_blink_show, nas_led_blink_store);
 
+static struct attribute *nasgpio_led_attrs[] = {
+	&dev_attr_blink.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(nasgpio_led);
+
 static int register_nasgpio_led(int led_nr)
 {
 	int ret;
@@ -481,20 +487,18 @@ static int register_nasgpio_led(int led_nr)
 		led->brightness = LED_FULL;
 	led->brightness_set = nasgpio_led_set_brightness;
 	led->blink_set = nasgpio_led_set_blink;
+	led->groups = nasgpio_led_groups;
 	ret = led_classdev_register(&nas_gpio_pci_dev->dev, led);
 	if (ret)
 		return ret;
-	ret = device_create_file(led->dev, &dev_attr_blink);
-	if (ret)
-		led_classdev_unregister(led);
-	return ret;
+
+	return 0;
 }
 
 static void unregister_nasgpio_led(int led_nr)
 {
 	struct led_classdev *led = get_classdev_for_led_nr(led_nr);
 	led_classdev_unregister(led);
-	device_remove_file(led->dev, &dev_attr_blink);
 }
 /*
  * module load/initialization