ANDROID: Separate cpu_scale and energy model setup

Keep the cpu_scale calculation in the arch_topology driver the way it is
done in mainline. This will require appropriate capacity-dmips-mhz
properties in the dt file.

Do the energy model setup completely separate in kernel/sched/energy.c.

This will allow to adapt the non-mainline energy model code more easily.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Change-Id: Ic69d9a619c0a57bb54e5aa6f320e95618394b7cb