sched: check for power inefficient task placement in tick

Although tasks are routed to the most power-efficient CPUs during
task wakeup, a CPU-bound task will not go through this decision point.
Load balancing can help if it is modified to dislodge a single task
from an inefficient CPU. The situation can be further improved if
during the tick, the task placement is checked to see if it is
optimal.

This sort of checking is already being done to ensure proper
task placement in heterogneous CPU topologies, so checking for
power efficient task placement fits pretty well.

Change-Id: I71e56d406d314702bc26dee1438c0eeda7699027
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>