AnyMotionDetector holds wakelock until conclusive.

Bug: 27821976

AMD held wakelock only during accelerometer data
acquisition, which allowed sleep to occur between its two
orientation measurements (http://go/anymotiondetector).
We now hold wakelock for its entire measurement, from
checkForAnyMotion() until it returns either STATIONARY or MOVING
or stop() is called.

Change-Id: Ib9c90de2c581d92f25212b91b9cc5e23642b5c77