sched: bias small task wakeups to same cluster as their waker

There may be performance benefits to scheduling small tasks in
the same CPU cluster as the task that is waking them. Change the
small task CPU selection logic to accomodate this.

Change-Id: I506777024f05868af593e740b90691b6554ddf8c
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>