mboxd: Rename mboxd_msg to transport_mbox

Change-Id: I0f4e206648c02a98fa938a7e582470c8d90904f1
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/Makefile.am b/Makefile.am
index 5e12147..97be7e0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -8,7 +8,7 @@
 	control_legacy.c \
 	control_dbus.c \
 	lpc.c \
-	mboxd_msg.c \
+	transport_mbox.c \
 	windows.c \
 	mtd.c
 mboxd_LDFLAGS = $(LIBSYSTEMD_LIBS)