sched: Introduce PANIC_ON_SCHED_BUG

Introduce PANIC_ON_SCHED_BUG to catch issues related to scheduler
like calling sleepable functions inside atomic context etc.

Change-Id: I9f1fe96772b317b17bd0e7423a48023d3cf141c7
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>