sched: fix stale predicted load in trace_sched_get_busy()

When early detection notification is pending, we skip calculating
predicted load. Initialize it to 0 so that stale value does not
get printed in trace_sched_get_busy().

Change-Id: I36287c0081f6c12191235104666172b7cae2a583
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>