fbd-dev-leds: fix brightness parameter

The fbd_dev_led_set_brightness function is only getting called with
parameter 0 at the moment so this was never noticed.

src/fbd-dev-leds.c

@@ -63,7 +63,7 @@ fbd_dev_led_set_brightness (FbdDevLed *led, guint brightness)
 {
   g_autoptr (GError) err = NULL;
 
-  if (!fbd_udev_set_sysfs_path_attr_as_int (led->dev, LED_BRIGHTNESS_ATTR, 0, &err)) {
+  if (!fbd_udev_set_sysfs_path_attr_as_int (led->dev, LED_BRIGHTNESS_ATTR, brightness, &err)) {
     g_warning ("Failed to setup brightness: %s", err->message);
     return FALSE;
   }