move AOSP audio preprocessing to vendor image

Test: build and check pre processing on ryu build
Change-Id: Idb7c4b3acc03a53edfe9389861d0830fdc888d61
diff --git a/media/libeffects/preprocessing/Android.mk b/media/libeffects/preprocessing/Android.mk
index 60030ac..3be3553 100644
--- a/media/libeffects/preprocessing/Android.mk
+++ b/media/libeffects/preprocessing/Android.mk
@@ -3,6 +3,7 @@
 # audio preprocessing wrapper
 include $(CLEAR_VARS)
 
+LOCAL_VENDOR_MODULE := true
 LOCAL_MODULE:= libaudiopreprocessing
 LOCAL_MODULE_TAGS := optional
 LOCAL_MODULE_RELATIVE_PATH := soundfx