hammerhead: disable cpu-boost

* The CPU-boost driver doesn't seem to behave correctly quite yet,
  disable it until it can be fixed.

Change-Id: Idec7151b6324d182828c748ff781de92d320e4f9
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_device_lge_hammerhead into cd-4.4