Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index bf40e06..1e440bb 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -1,13 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  *	stacktrace.c : stacktracing APIs needed by rest of kernel
  *			(wrappers over ARC dwarf based unwinder)
  *
  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
  *  vineetg: aug 2009
  *  -Implemented CONFIG_STACKTRACE APIs, primarily save_stack_trace_tsk( )
  *   for displaying task's kernel mode call stack in /proc/<pid>/stack