frameworks/av: convert LOCAL_MODULE_PATH to LOCAL_MODULE_RELATIVE_PATH

LOCAL_MODULE_PATH doesn't work for multiarch builds, replace it
with LOCAL_MODULE_RELATIVE_PATH.

Change-Id: I4e4ceec61d026bbe74ba604554c06104bde42e5e
diff --git a/media/libeffects/preprocessing/Android.mk b/media/libeffects/preprocessing/Android.mk
index c344352..9e8cb83 100644
--- a/media/libeffects/preprocessing/Android.mk
+++ b/media/libeffects/preprocessing/Android.mk
@@ -5,7 +5,7 @@
 
 LOCAL_MODULE:= libaudiopreprocessing
 LOCAL_MODULE_TAGS := optional
-LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)/soundfx
+LOCAL_MODULE_RELATIVE_PATH := soundfx
 
 LOCAL_SRC_FILES:= \
     PreProcessing.cpp