- make sure to call onAccuracyChanged only when it actually changes
- only call onAccuracyChanged on Magnetic and Orientation sensors, which
are the only ones to support it.
- for other sensors, call onAccuracyChanged only once with the
SENSOR_STATUS_ACCURACY_HIGH value
Change-Id: Ic861e3d48d3b98dab74ffebe2746576f5b69f371