Revert "Let there be light - Hardware keyboard brightness support"

This reverts commit aef838597545e1d461532656294c098ffffa6fea.
power: Add CPU boosting interface

 * Boosts CPU using Power HAL for the given duration.
 * Duration is given in microseconds.
 * Power HAL must implement POWER_HINT_CPU_BOOST.

Change-Id: Ic79baf7e3d0f75483c2fe8a242b4c3d93368b68b
Add CPU boosting hooks

 * Boost CPU to max during scrolling
 * Boost CPU to max on activity start/resume
 * Inspired by a patch from CodeAuora.

Change-Id: I72f2c2851b01fbceabddead03a4c3a7a0526ca61
PowerManagerService: Implement setButtonBrightnessOverrideFromWindowManager method

Differs from Android 4.1 (and earlier) implementation in that the
overridden button light still turns off after BUTTON_ON_DURATION instead of
staying on until screen off.  However, button lights are annoying, and
really the purpose of this is to allow apps (e.g., Screen Filter) to
_disable_ the button lights altogether.
Keyboard light: Fix the physical keyboard not light when it's visiable.

Change-Id: I595afd3cb6b422a17ae0f6ec20aa51979db13810