sched: fix bail condition in bail_inter_cluster_balance()

Following commit efcad25cbfb (revert "sched: influence cpu_power based
on max_freq and efficiency), all CPUs in the system have the same
cpu_power and consequently the same group capacity. Therefore, the
check in bail_inter_cluster_balance() can now no longer be used to
distinguish a higher performance cluster from one with lower
performance. The check is currently broken and always returns true for
every load balancing attempt. Fix this by using runqueue capacity
instead which can still be used as a good measure of cluster
capabilities.

Also the logic for distinguishing between idle environments and using
a different sched group capacity in update_sd_pick_busiest() is
redundant. sgs->group_capacity would now always be equal to the number
of CPUs in the group. Use sgs->group_capacity directly in conditonal
checks in that function.

Change-Id: Idecfd1ed221d27d4324b20539e5224a92bf8b751
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>