sched: Delete heavy task heuristics in prediction code

Heavy task prediction code needs further tuning to avoid any
negative power impact. Delete the code for now instead of adding
tunables to avoid inefficiencies in the scheduler path.

Change-Id: I71e3b37a5c99e24bc5be93cc825d7e171e8ff7ce
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>