AudioService: fix NPE in AudioDeviceBroker.setCommunicationRouteForClient

Commit 19a459b7 added code that should only be executed upon selection
of a valid LE device for communication and not when resetting the
device.

Bug: 295288081
Test: place a call and select/unselect a BT LE audio device
Change-Id: I8c560004a6c87b5b33ab9c862b1e4fde2075bb31

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

@@ -435,7 +435,7 @@ public class AudioDeviceBroker {
         // LE Audio it stays the same and we must trigger the proper stream volume alignment, if
         // LE Audio communication device is activated after the audio system has already switched to
         // MODE_IN_CALL mode.
-        if (isBluetoothLeAudioRequested()) {
+        if (isBluetoothLeAudioRequested() && device != null) {
             final int streamType = mAudioService.getBluetoothContextualVolumeStream();
             final int leAudioVolIndex = getVssVolumeForDevice(streamType, device.getInternalType());
             final int leAudioMaxVolIndex = getMaxVssVolumeForStream(streamType);