Align LibAudioHal V2 and V4 for factorisation

In order to merge the two version, they must first align as much
as possible.

Test: playback music, assistant
Change-Id: If517cc3f4646a224af3e9b3d42b68a75f1801b39
Signed-off-by: Kevin Rocard <krocard@google.com>
diff --git a/media/libaudiohal/2.0/DeviceHalHidl.h b/media/libaudiohal/2.0/DeviceHalHidl.h
index 3c1cb59..d6b0ab0 100644
--- a/media/libaudiohal/2.0/DeviceHalHidl.h
+++ b/media/libaudiohal/2.0/DeviceHalHidl.h
@@ -28,6 +28,7 @@
 using ::android::hardware::Return;
 
 namespace android {
+namespace V2_0 {
 
 class DeviceHalHidl : public DeviceHalInterface, public ConversionHelperHidl
 {
@@ -124,6 +125,7 @@
     virtual ~DeviceHalHidl();
 };
 
+} // namespace V2_0
 } // namespace android
 
 #endif // ANDROID_HARDWARE_DEVICE_HAL_HIDL_H