libhardware: Add power hint to set profile

 * A PowerHAL can implement support for this hint to receive
   power profile changes from the framework.

Change-Id: Ie1e9e3b827c731cf5a817a0491677e3451fe8678
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_hardware_libhardware into temp