audio: Only build when TARGET_QCOM_AUDIO_VARIANT=caf

Change-Id: I7da0ef9e8ed7017aa847b3deeaf71d8708a75d9d
diff --git a/Android.mk b/Android.mk
index 356b7de..e503f8a 100644
--- a/Android.mk
+++ b/Android.mk
@@ -1,6 +1,6 @@
 ifneq ($(filter msm8960,$(TARGET_BOARD_PLATFORM)),)
-
+ifeq ($(TARGET_QCOM_AUDIO_VARIANT),caf)
 AUDIO_ROOT := $(call my-dir)
 include $(call all-subdir-makefiles)
-
+endif
 endif