Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/clk/st/clkgen-mux.c b/drivers/clk/st/clkgen-mux.c
index c514d39..ce583de 100644
--- a/drivers/clk/st/clkgen-mux.c
+++ b/drivers/clk/st/clkgen-mux.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * clkgen-mux.c: ST GEN-MUX Clock driver
  *
@@ -5,15 +6,10 @@
  *
  * Authors: Stephen Gallimore <stephen.gallimore@st.com>
  *	    Pankaj Dev <pankaj.dev@st.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
  */
 
 #include <linux/slab.h>
+#include <linux/io.h>
 #include <linux/of_address.h>
 #include <linux/clk.h>
 #include <linux/clk-provider.h>