sched: ceil idle index to prevent from out of bound accessing

It's possible size of given idle cost index is smaller than CPU's
possible idle index size.  Ceil the CPU's idle index to prevent out
of bound accessing.

Change-Id: Idecb4f68758dd0183886ea74d0e9da3d236b0062
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>
(cherry picked from commit ecedc7afd841c8d7ef0145924620304608d269ef)

Author: Joonwoo Park

kernel/sched/fair.c

@@ -5892,6 +5892,9 @@ static int calc_sg_energy(struct energy_env *eenv)
 		idle_idx = group_idle_state(eenv, cpu_idx);
 		if (unlikely(idle_idx < 0))
 			return idle_idx;
+		if (idle_idx > sg->sge->nr_idle_states - 1)
+			idle_idx = sg->sge->nr_idle_states - 1;
+
 		idle_power = sg->sge->idle_states[idle_idx].power;
 
 		idle_energy   = SCHED_CAPACITY_SCALE - sg_util;