servicemanager: Add listen service to the service table

- Listen is a voice activation feature.
- When an application registers a "keyword" with
  ListenService, then events are sent to application
  when that keywork is spoken by user and detected
  by ListenEngine.
- ListenService runs within the MediaServer process.
  The ListenService needs to be added to service table
  in order for application thread to have permission
  to access Listen functionality.

Change-Id: I8c79bebc92920d0b62b12ef925cb35a59644ee86