sched/fair: fix incorrect CPU selection for non latency sensitive tasks

The Non latency sensitive tasks CPU selection targets for an active
CPU in the little cluster. The shallowest c-state CPU is stored as
a backup. However if all CPUs in the little cluster are idle, we pick
an active CPU in the BIG cluster as the target CPU. This incorrect
choice of the target CPU may not get corrected by the
select_energy_cpu_idx() depending on the energy difference between
previous CPU and target CPU.

This can be fixed easily by maintaining the same variable that tracks
maximum capacity of the traversed CPU for both idle and active CPUs.

Change-Id: I3efb8bc82ff005383163921ef2bd39fcac4589ad
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>