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

Conflicts:
	services/jni/com_android_server_power_PowerManagerService.cpp

Conflicts:
	core/java/android/os/IPowerManager.aidl
	core/java/android/os/PowerManager.java
	services/java/com/android/server/power/PowerManagerService.java
	tools/layoutlib/bridge/src/com/android/layoutlib/bridge/android/BridgePowerManager.java