Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/usb/serial/keyspan_pda.c b/drivers/usb/serial/keyspan_pda.c
index 38d43c4..bf988f7 100644
--- a/drivers/usb/serial/keyspan_pda.c
+++ b/drivers/usb/serial/keyspan_pda.c
@@ -6,7 +6,7 @@
  * Copyright (C) 1999, 2000 Brian Warner	<warner@lothar.com>
  * Copyright (C) 2000 Al Borchers		<borchers@steinerpoint.com>
  *
- * See Documentation/usb/usb-serial.txt for more information on using this
+ * See Documentation/usb/usb-serial.rst for more information on using this
  * driver
  */