libAudioHal: factorize V2 and V4

Merge the two versions and ifdef the few
parts still different.

Test: playback music, assistant
Change-Id: I750f5d18ba34236637c18a87e2daa54a7c446d91
Signed-off-by: Kevin Rocard <krocard@google.com>
diff --git a/media/libaudiohal/DevicesFactoryHalInterface.cpp b/media/libaudiohal/DevicesFactoryHalInterface.cpp
index 9f70e4f..e631ace 100644
--- a/media/libaudiohal/DevicesFactoryHalInterface.cpp
+++ b/media/libaudiohal/DevicesFactoryHalInterface.cpp
@@ -17,8 +17,7 @@
 #include <android/hardware/audio/2.0/IDevicesFactory.h>
 #include <android/hardware/audio/4.0/IDevicesFactory.h>
 
-#include <libaudiohal/2.0/FactoryHalHidl.h>
-#include <libaudiohal/4.0/FactoryHalHidl.h>
+#include <libaudiohal/FactoryHalHidl.h>
 
 namespace android {