Revert "audio hal: move audio hal to vendor"

This reverts commit 6a2423f1bf493b95315599205dd01bb924fab854.
The original change is not complete!

Bug: 35650034
Test: Play ringtone on Sailfish
diff --git a/hal/Android.mk b/hal/Android.mk
index e775b11..c2801db 100644
--- a/hal/Android.mk
+++ b/hal/Android.mk
@@ -148,7 +148,7 @@
 
 LOCAL_MODULE := audio.primary.$(TARGET_BOARD_PLATFORM)
 
-LOCAL_PROPRIETARY_MODULE := true
+LOCAL_MODULE_RELATIVE_PATH := hw
 
 LOCAL_MODULE_TAGS := optional