Fix PositionSensor.getMotor()

[trbljump]

Was calling the wrong function to get the associated motor.

Description PositionSensor.getMotor() was calling the wrong c function and failing.

Tasks Add the list of tasks of this PR.

• [x] Update the changelog

Documentation Aligns the code with the existing documentation.

Screenshots n/a

Additional context n/a

[omichel]

Well spotted! Could you please also add a line in the change log?