sched: CONFIG_SCHED_GROUP_FAIR=y fixlet

when I built with CONFIG_FAIR_GROUP_SCHED=y, I need the following change
to make things right.

[ From: mingo@elte.hu ]

this config option is not upstream-configurable right now but lets fix
this for completeness.
Signed-off-by: NBruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched_fair.c

@@ -1057,7 +1057,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
  */
 static void set_curr_task_fair(struct rq *rq)
 {
-	struct sched_entity *se = &rq->curr.se;
+	struct sched_entity *se = &rq->curr->se;
 
 	for_each_sched_entity(se)
 		set_next_entity(cfs_rq_of(se), se);