Fixed null pointer exception in AAE KitchenSink.

Car was crashing due mCar being null in volume test fragment.

Bug: 149538050
Test: m -j
Test: run EmbeddedKitchenSinkApp volume test fragment.
Change-Id: Icb1ea08f1403b04b09fd87d2aa3b1ec0e439af97
(cherry picked from commit d51818a55471c7719696b92bb5c35212194ae426)
diff --git a/tests/EmbeddedKitchenSinkApp/src/com/google/android/car/kitchensink/volume/VolumeTestFragment.java b/tests/EmbeddedKitchenSinkApp/src/com/google/android/car/kitchensink/volume/VolumeTestFragment.java
index df9aa7b..f753efe 100644
--- a/tests/EmbeddedKitchenSinkApp/src/com/google/android/car/kitchensink/volume/VolumeTestFragment.java
+++ b/tests/EmbeddedKitchenSinkApp/src/com/google/android/car/kitchensink/volume/VolumeTestFragment.java
@@ -116,7 +116,7 @@
             return;
         }
         Log.d(TAG, "Connected to Car Service");
-        mCarAudioManager = (CarAudioManager) mCar.getCarManager(Car.AUDIO_SERVICE);
+        mCarAudioManager = (CarAudioManager) car.getCarManager(Car.AUDIO_SERVICE);
         initVolumeInfo();
     };