Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/ide/ide-io-std.c b/drivers/ide/ide-io-std.c
index 1976397..18c20a7 100644
--- a/drivers/ide/ide-io-std.c
+++ b/drivers/ide/ide-io-std.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 
 #include <linux/kernel.h>
 #include <linux/export.h>