led: core: Fix brightness setting when setting delay_off=0

[ Upstream commit 2b83ff96 ]

With the current code, the following sequence won't work :
echo timer > trigger

echo 0 >  delay_off
* at this point we call
** led_delay_off_store
** led_blink_set

drivers/leds/led-core.c

@@ -149,7 +149,7 @@ void led_blink_set(struct led_classdev *led_cdev,
 		   unsigned long *delay_on,
 		   unsigned long *delay_off)
 {
-	del_timer_sync(&led_cdev->blink_timer);
+	led_stop_software_blink(led_cdev);
 
 	led_cdev->flags &= ~LED_BLINK_ONESHOT;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;