sched: clean up compiler warning

Reported-by: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 147004c6..93ac8ee 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -253,7 +253,7 @@
 
 		diff = iter->rt_runtime - iter->rt_time;
 		if (diff > 0) {
-			do_div(diff, weight);
+			diff = div_u64((u64)diff, weight);
 			if (rt_rq->rt_runtime + diff > rt_period)
 				diff = rt_period - rt_rq->rt_runtime;
 			iter->rt_runtime -= diff;