add missing newline in debug statement for RS232 TX

diff --git a/src/rs232.c b/src/rs232.c
index 24a3b05..2a64de5 100644
--- a/src/rs232.c
+++ b/src/rs232.c
@@ -101,7 +101,7 @@
 		return 0;
 	}
 
-	DEBUGP(DMI, "RS232 TX: %s", hexdump(msg->data, msg->len));
+	DEBUGP(DMI, "RS232 TX: %s\n", hexdump(msg->data, msg->len));
 
 	/* send over serial line */
 	written = write(bfd->fd, msg->data, msg->len);