ANDROID: Move energy model init call into arch_topology driver

Now that we decouple the Energy Model (EM) from the cpu_scale
calculation, initialize the EM after the cpu_scale calaculation
has finished.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Change-Id: Ia39c969f5c674e6e644951fd8b3e986d16cdab3b