Return acceleration as meter per second per second

Acceleration is currently returned as raw values. If a conversion can be found, use that to update returns to m^s to comply with CP Design Guide:
https://circuitpython.readthedocs.io/en/latest/docs/design_guide.html#sensor-properties-and-units

Start by reviewing the acceleration property or return path and the linked CircuitPython Design Guide section on sensor properties and units. Determine the required conversion from the raw values; done means acceleration is returned in meters per second per second rather than raw values, with any relevant tests updated or added.

Written by the indexing model from the issue text.