hal: audio_extn: Build auto_hal only for automotive

Allow auto_hal lib to build only if
"AUDIO_FEATURE_ENABLED_AUTO_HAL" is true
to prevent unneccessary building for mobile.

Change-Id: I0129ead84e6827e8d8ae33bc2fd2ec1e738a3443
diff --git a/hal/audio_extn/Android.mk b/hal/audio_extn/Android.mk
index 597b6bd..aba6592 100755
--- a/hal/audio_extn/Android.mk
+++ b/hal/audio_extn/Android.mk
@@ -1080,6 +1080,7 @@
 
 #            Build AUTO_HAL LIB
 #-------------------------------------------
+ifeq ($(strip $(AUDIO_FEATURE_ENABLED_AUTO_HAL)), true)
 include $(CLEAR_VARS)
 
 LOCAL_MODULE := libautohal
@@ -1137,3 +1138,4 @@
 LOCAL_SANITIZE := integer_overflow
 endif
 include $(BUILD_SHARED_LIBRARY)
+endif