sched: remove conversion to bool in is_full_throttle_boost

is_full_throttle_boost checks for sched_boost() and returns either true
or false which can be achieved by just return the check itself.

Change-Id: I8e996a5ae8713a972fb0ef181e709bcd61ed7005
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>