Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/sound/sparc/amd7930.c b/sound/sparc/amd7930.c
index 56f1741..441222c 100644
--- a/sound/sparc/amd7930.c
+++ b/sound/sparc/amd7930.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Driver for AMD7930 sound chips found on Sparcs.
  * Copyright (C) 2002, 2008 David S. Miller <davem@davemloft.net>