intelli_plug: Apply boost_lock only to cpu_down

* With intelli_plug, we have cpu_up and cpu_down in single
  function.
* If we use boost_lock in same function, cpu_up is blocked
  as well.
* So separate boost_lock_check and apply it only to
  cpu_down.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>