hal: Correct AC4 definition in audio extn header

Correct the AC4 definition in the audio extention
header to match the definition in the Android
header.

Change-Id: I3365ecb990d64e758f9eb172888cfb7b3ea989b0
diff --git a/hal/audio_extn/audio_extn.h b/hal/audio_extn/audio_extn.h
index 5707742..f1a8382 100644
--- a/hal/audio_extn/audio_extn.h
+++ b/hal/audio_extn/audio_extn.h
@@ -96,7 +96,7 @@
 #endif
 
 #ifndef AUDIO_FORMAT_AC4
-#define AUDIO_FORMAT_AC4  0x23000000UL
+#define AUDIO_FORMAT_AC4  0x22000000UL
 #endif
 
 #ifndef AUDIO_OUTPUT_FLAG_TIMESTAMP