Revert "sched: warn/panic upon excessive scheduling latency"

This reverts commit ab9e1373 ("sched: warn/panic upon excessive
scheduling latency") as this feature is no longer used.

Change-Id: Ibf7d8340b87f6772a42e6edb22f9f3cd73e05512
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>