sched: fix calc_delta_mine()

lw->weight can be 0 for a short time during bootup.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

kernel/sched.c

@@ -1084,7 +1084,7 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight,
 	u64 tmp;
 
 	if (unlikely(!lw->inv_weight))
-		lw->inv_weight = (WMULT_CONST - lw->weight/2) / lw->weight + 1;
+		lw->inv_weight = (WMULT_CONST-lw->weight/2) / (lw->weight+1);
 
 	tmp = (u64)delta_exec * weight;
 	/*