led: core: Clear LED_BLINK_SW flag in led_blink_set()

[Only needed in 4.9.y due to other fixes in mainline - gregkh]

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

@@ -188,6 +188,7 @@ void led_blink_set(struct led_classdev *led_cdev,
 {
 	del_timer_sync(&led_cdev->blink_timer);
 
+	led_cdev->flags &= ~LED_BLINK_SW;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT;
 	led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;