sched: pack the idle load balance

Look for an idle CPU close the pack buddy CPU whenever possible.
The goal is to prevent the wake up of a CPU which doesn't share the power
line of the pack CPU

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
backported for Tuna Hybrid kernel by faux123
Revert "Revert "ARM: 7169/1: topdown mmap support""

This reverts commit 4a4bc30aee923169bdf5d20912062359d549b942.