cpufreq: cpu-boost: Export cpu boost status

* This will help hotplug drivers to know boost status
  of CPU and act accordingly.

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
msm: hotplug: Do not butcher boosted CPU

* In existing scenario, we don't check whether CPU is
  booster or not before taking it down.
* Break the loop and wait for next cycle if CPU is
  currently being boosted.

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