Revert "leds: use led_set_brightness in led_trigger_event"

This reverts commit a0193cbee0809d65362a0767b2d50306b145b2f5.

The problem with the original commit was that it caused a warning with
the MMC trigger calling del_timer_sync from hard-irq context.

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Reported-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>

drivers/leds/led-triggers.c

@@ -224,7 +224,7 @@ void led_trigger_event(struct led_trigger *trig,
 		struct led_classdev *led_cdev;
 
 		led_cdev = list_entry(entry, struct led_classdev, trig_list);
-		led_set_brightness(led_cdev, brightness);
+		__led_set_brightness(led_cdev, brightness);
 	}
 	read_unlock(&trig->leddev_list_lock);
 }