audio: hal: enable ext FM usecase via audio patch

Support external FM Tuner usecase via device
to device audio patch configuration.

Change-Id: I876ca3f1b4aeb79593a75128ff640083803e07fe
diff --git a/hal/Android.mk b/hal/Android.mk
index 1a0c2e2..35b84b6 100644
--- a/hal/Android.mk
+++ b/hal/Android.mk
@@ -354,6 +354,10 @@
 LOCAL_SHARED_LIBRARIES += libbase libhidlbase libhwbinder libutils android.hardware.power@1.2 liblog
 LOCAL_SRC_FILES += audio_perf.cpp
 
+ifeq ($(strip $(AUDIO_FEATURE_ENABLED_FM_TUNER_EXT)),true)
+    LOCAL_CFLAGS += -DFM_TUNER_EXT_ENABLED
+endif
+
 LOCAL_MODULE := audio.primary.$(TARGET_BOARD_PLATFORM)
 
 LOCAL_MODULE_RELATIVE_PATH := hw