Add support for USB OTG

Change-Id: Id5ded1d14f01e4bd126115866e0bf3bd75d5cfcb
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
hammerhead: Enable ZSL mode for camera

 * With recent kernel changes, we no longer crash when letting the
   preview run during continuous shots. Enjoy rapid-fire shooting.

Change-Id: Ib57869f185166539d761fd5a2766c586501023da