Revert "sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg"

This reverts commit 079651c6 which is
commit 70fb5ccf upstream.

It breaks the Android GKI kernel abi, and is not needed for Android
devices, so revert it for now.  If it is needed for this branch, it can
come back later in an ABI-stable way.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ie4a8739747859bfd57e48a2745b7fcf90233fd6c