MTP: Build flag for setting custom MTP device/path

Change-Id: Ic19ec61dc6cb08df00eb1326d96262b46bb93bfb
diff --git a/mtp/Android.mk b/mtp/Android.mk
index ebf1a6d..683999d 100755
--- a/mtp/Android.mk
+++ b/mtp/Android.mk
@@ -30,6 +30,11 @@
     mtp_MtpDatabase.cpp \
     node.cpp
 LOCAL_SHARED_LIBRARIES += libz libc libusbhost libstdc++ libstlport libdl libcutils libutils
+
+ifneq ($(TW_MTP_DEVICE),)
+	LOCAL_CFLAGS += -DUSB_MTP_DEVICE=$(TW_MTP_DEVICE)
+endif
+
 include $(BUILD_SHARED_LIBRARY)
 
 # Build twrpmtp binary / executable