core_ctl: Add refcounting to boost api

More than one client may call the core_ctl_set_boost api. Add support
for this.
Also add a new trace event that is emitted when this api is called.

Change-Id: Ic8ed105e63b469695ad15589725f651825604f08
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>