cpu-boosting: Modify cpu boosting level to handle cpu contention

cpu-boosting: Modify cpu boosting level to handle cpu contention

Modify cpu boosting level to handle cpu contention.
The cpu boosting governor makes a list of commands to handle cpu contention,
and it decreases cpu boosting level of some threads (victims).

The cpu boosting module waits for timer events to check whehter cpu contention
is alleviated or not. If so, restoring cpu boosting level.
If not, making a new timer to check cpu contention after some interval.

Currently, cpu boosting module just checks whether PSI events are not
triggered for some interval. It is not the best solution, but simple
and intuitive solution.

Change-Id: I897c89c054ab11ed08ad16ef171610d7fa2944bd
Signed-off-by: Unsung Lee <unsung.lee@samsung.com>