sched: Print aggregation status in sched_get_busy trace event

Aggregation for frequency is not enabled all the time. The aggregated
load is attached to the most busy CPU only when the group load is above
a certain threshold. Print the aggregation status in sched_get_busy
trace event to make debugging and testing easier.

Change-Id: Icb916f362ea0fa8b5dc7d23cb384168d86159687
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>