hal: Add stub function for AANC noise level API

Add stub function for AANC noise level API to avoid compilation
error when the ANC feature is not defined.

Change-Id: I1bb5dec8685eb7404b8c9e3d3871487ee3af90b2
diff --git a/hal/audio_extn/audio_extn.h b/hal/audio_extn/audio_extn.h
index e7d2386..b4cb231 100644
--- a/hal/audio_extn/audio_extn.h
+++ b/hal/audio_extn/audio_extn.h
@@ -156,10 +156,13 @@
 #define audio_extn_get_anc_enabled()                     (0)
 #define audio_extn_should_use_fb_anc()                   (0)
 #define audio_extn_should_use_handset_anc(in_channels)   (0)
+#define audio_extn_set_aanc_noise_level(adev, parms)     (0)
 #else
 bool audio_extn_get_anc_enabled(void);
 bool audio_extn_should_use_fb_anc(void);
 bool audio_extn_should_use_handset_anc(int in_channels);
+void audio_extn_set_aanc_noise_level(struct audio_device *adev,
+                                     struct str_parms *parms);
 #endif
 
 #ifndef VBAT_MONITOR_ENABLED