Fixed overclocking Power HAL module

Change-Id: I7fc7c517e04eee3933ab7107e788b50e41270b67
tuna: power: make sure we don't apply the screen off freq on screen on

This fixes issues when pressing the power button repeatedly in a short
period of time. The "on" call might not run, and when we re-read the
value on screen off to store it, we will be actually reading the capped
screen off value. Make sure that's not the case.
Review power freq on screen off code

Review general code
removed non sense comparation  "on ?" since is extra

Change-Id: I285368dbb449e4234e9cea8846c087fc4f3200f3
tuna: add cpu boost hint

Code copied from Steve Kondik's commit.

Change-Id: I7576534132940ef0820af91f2d314055fbd84411

Conflicts:
	power/power_tuna.c