Revert "Audio V4: Split system and vendor Audio.h"

This reverts commit fc9e212f018ce41430ec8dcebc3cae3c346474bb.

Reason for revert: Breaks multiple devices

Change-Id: I816671fd92246f85c97d00819858a74e36e2929d
diff --git a/modules/usbaudio/Android.bp b/modules/usbaudio/Android.bp
index ecc74fb..c7d403f 100644
--- a/modules/usbaudio/Android.bp
+++ b/modules/usbaudio/Android.bp
@@ -25,7 +25,5 @@
         "libalsautils",
     ],
     cflags: ["-Wno-unused-parameter"],
-    header_libs: [
-        "android.hardware.audio.common.legacy@2.0",
-    ],
+    header_libs: ["libhardware_headers"],
 }