Get the highest direct rate level that a sensor support.
\param sensor a {@link ASensor} to denote the sensor to be checked.
\return a ASENSOR_DIRECT_RATE_... enum denoting the highest rate level supported by the sensor.
If return value is {@link ASENSOR_DIRECT_RATE_STOP}, it means the sensor
does not support direct report.
Get the highest direct rate level that a sensor support.
\param sensor a {@link ASensor} to denote the sensor to be checked.
\return a ASENSOR_DIRECT_RATE_... enum denoting the highest rate level supported by the sensor. If return value is {@link ASENSOR_DIRECT_RATE_STOP}, it means the sensor does not support direct report.