Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/usb/serial/keyspan_usa28msg.h b/drivers/usb/serial/keyspan_usa28msg.h
index dee454c..a19f3fe 100644
--- a/drivers/usb/serial/keyspan_usa28msg.h
+++ b/drivers/usb/serial/keyspan_usa28msg.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
 	usa28msg.h