audio: Add ACDB INIT extension

- Add an audio extension for ACDB
- ACDB Init from AHAL and STHAL are routed via this extension

Test:  verify audio playback and captrue

Change-Id: I5ee568d360651d6db7d351fb8aae1b508bf99589
Signed-off-by: David Lin <dtwlin@google.com>
diff --git a/hal/Android.mk b/hal/Android.mk
index 2b27e64..2de6c16 100644
--- a/hal/Android.mk
+++ b/hal/Android.mk
@@ -67,7 +67,8 @@
 	audio_extn/ext_speaker.c \
 	audio_extn/audio_extn.c \
 	audio_extn/utils.c \
-	$(AUDIO_PLATFORM)/platform.c
+	$(AUDIO_PLATFORM)/platform.c \
+        acdb.c
 
 ifdef MULTIPLE_HW_VARIANTS_ENABLED
   LOCAL_CFLAGS += -DHW_VARIANTS_ENABLED