ANDROID: sched/fair: Select correct capacity state for energy_diff

The util returned from group_max_util is not capped at the max util
present in the group, so it can be larger than the capacity stored in
the array. Ensure that when this happens, we always use the last entry
in the array to fetch energy from.

Tested with synthetics on Juno board.

Bug: 38159576
Change-Id: I89fb52fb7e68fa3e682e308acc232596672d03f7
Git-commit: 4f8767d1
Git-repo: https://android.googlesource.com/kernel/msm.git


Signed-off-by: Chris Redpath <chris.redpath@arm.com>
[srkupp@codeaurora.org: Resolved minor conflict]
Signed-off-by: Srinivasa Rao Kuppala <srkupp@codeaurora.org>