sched: fix update_stats_enqueue() reniced codepath

the key has to be rescaled to /weight even if it has a positive value.

(this change only affects the scheduling of reniced tasks)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index b885b3c..7a632c5 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -405,7 +405,8 @@
 					(WMULT_SHIFT - NICE_0_SHIFT);
 		} else {
 			tmp = se->wait_runtime;
-			key -= (tmp * se->load.weight) >> NICE_0_SHIFT;
+			key -= (tmp * se->load.inv_weight) >>
+					(WMULT_SHIFT - NICE_0_SHIFT);
 		}
 	}