ANDROID: sched: Extend sched_group_energy to test load-balancing decisions

Extended sched_group_energy() to support energy prediction with usage
(tasks) added/removed from a specific cpu or migrated between a pair of
cpus. Useful for load-balancing decision making.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Change-Id: I31afd581448d894a97afa7f5f7dac4666191e6a0
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
Git-commit: e3126a01
Git-repo: https://android.googlesource.com/kernel/common/


[satyap@codeaurora.org: Trivial merge conflict resolution]
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>