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

This reverts commit c246f5eaa1dabda72eb3bcf3823d4cab65bd4e83.

Reason for revert: Breaks the build of multiple devices

Change-Id: I516d7467369f9a9b9872e7378c8b2eabc8b1d96e
diff --git a/voice_processing/Android.mk b/voice_processing/Android.mk
index 17ea957..02adf18 100644
--- a/voice_processing/Android.mk
+++ b/voice_processing/Android.mk
@@ -18,6 +18,9 @@
     -Wno-unused-function \
     -Wno-unused-variable \
 
+LOCAL_C_INCLUDES += \
+    $(call include-path-for, audio-effects)
+
 LOCAL_SHARED_LIBRARIES := \
     liblog \
     libcutils
@@ -26,8 +29,5 @@
 
 LOCAL_CFLAGS += -fvisibility=hidden
 
-LOCAL_HEADER_LIBRARIES += \
-    libhardware_headers \
-    android.hardware.audio.effect.legacy@2.0 \
-
+LOCAL_HEADER_LIBRARIES += libhardware_headers
 include $(BUILD_SHARED_LIBRARY)