deregisterDevice
Requests the OEM's backend to unregister this device for Alexa Preview Mode using the AVS InstantDeviceRegistration API.
Return
PreviewModeResult.Success if the deregistration of this device was successful or PreviewModeResult.Failure if the process failed.
Parameters
deviceSerialNumber
Unique serial number of this device. The client's backend should be able to recognize each device using this info.