Build BT if exists.

Change-Id: I987e8aa41dd827ee3ba9edeff82f778f8f236a20
diff --git a/peripheral/bluetooth/ap6212/peripheral.mk b/peripheral/bluetooth/ap6212/peripheral.mk
index 7960289..35b5dea 100644
--- a/peripheral/bluetooth/ap6212/peripheral.mk
+++ b/peripheral/bluetooth/ap6212/peripheral.mk
@@ -14,13 +14,17 @@
 # limitations under the License.
 #
 
+LOCAL_PATH := $(call my-dir)
+
 AP6212_BT_SRC := hardware/bsp/rockchip/peripheral/bluetooth/ap6212
 AP6212_BT_FW_SRC := vendor/bsp/rockchip/peripheral/bluetooth/ap6212_firmware
 AP6212_BT_FW_DST := system/vendor/firmware
 
+ifneq ($(wildcard $(LOCAL_PATH)/../../../../../../$(AP6212_BT_SRC)),)
 PRODUCT_COPY_FILES += \
     $(AP6212_BT_FW_SRC)/bcm43438a0.hcd:$(AP6212_BT_FW_DST)/bcm43438a0.hcd \
     $(AP6212_BT_SRC)/bt_vendor.conf:system/etc/bluetooth/bt_vendor.conf
+endif
 
 #BCM bluetooth
 BOARD_HAVE_BLUETOOTH_BCM := true