sched: Start using the primary cluster first on SMP

The primary cluster is the cluster for which energy is
lower compared to the other cluster. Containing the load
to this cluster before spilling to the other cluster
have power benefit.

Change-Id: I8bcde280d1ea29e5f3a5bb62eec803345073820e
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>