sched: Don't construct or check for energy-tables if !EAS

If the energy-aware scheduler isn't in use, don't attempt
to init the scheduler energy structures from DT, and don't
check them when rebuilding domains on hotplug-{in|out}.

Change-Id: I4f5dcc057191746e89548d1ea51443757776e159
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>