Merge "sched: walt: Add BUG_ON() when wallclock goes backwards"

	u64 old_window_start = rq->window_start;

	delta = wallclock - rq->window_start;

	/*

	 * If the MPM global timer is cleared, set delta as 0 to

	 * avoid kernel BUG happening

	 */

	if (delta < 0) {

		delta = 0;

		WARN_ONCE(1, "WALT wallclock appears to have gone backwards or reset\n");

	}

	BUG_ON(delta < 0);

	if (delta < sched_ravg_window)

		return old_window_start;