fix bugfix with unique_id (#3217)

homeassistant/components/media_player/sonos.py

@@ -199,6 +199,7 @@ class SonosDevice(MediaPlayerDevice):
         self.hass = hass
         self.volume_increment = 5
         self._player = player
+        self._name = None
         self.update()
         self.soco_snapshot = Snapshot(self._player)
 
@@ -216,11 +217,6 @@ class SonosDevice(MediaPlayerDevice):
         """Return the name of the device."""
         return self._name
 
-    @property
-    def unique_id(self):
-        """Return a unique ID."""
-        return "{}.{}".format(self.__class__, self._player.uid)
-
     @property
     def state(self):
         """Return the state of the device."""