AudioService: Remove Analog Dock from fixed-volume devices

* Many devices identifying as "Analog Docks" have not built in volume controls
  and rely on software volume (See: All Motorola Mods, older 3.5mm docks,
  etc.)

Change-Id: Ie9b97c7b17b882a5d804db398d149bd777ccf5a4
(cherry picked from commit 24ce6c3ea58f339cc8a537205e30d2516d2b073b)
(cherry picked from commit a6eff9c92353cd74ebae12cc82840d1356844980)

services/core/java/com/android/server/audio/AudioService.java

@@ -694,7 +694,6 @@ public class AudioService extends IAudioService.Stub
     // Devices for which the volume is fixed (volume is either max or muted)
     Set<Integer> mFixedVolumeDevices = new HashSet<>(Arrays.asList(
-            AudioSystem.DEVICE_OUT_ANLG_DOCK_HEADSET,
             AudioSystem.DEVICE_OUT_AUX_LINE));
     // Devices for which the volume is always max, no volume panel
     Set<Integer> mFullVolumeDevices = new HashSet<>(Arrays.asList(