sched: Add sched_enq_deq_task trace point

To debug issues related to task scheduling sched_enq_deq_task
trace point is very useful.

Change-Id: I668702701d5443a4f5b0356634622f071297eb28
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>