Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/tools/perf/arch/xtensa/Build b/tools/perf/arch/xtensa/Build
index 54afe4a..e4e5f33 100644
--- a/tools/perf/arch/xtensa/Build
+++ b/tools/perf/arch/xtensa/Build
@@ -1 +1 @@
-libperf-y += util/
+perf-y += util/
diff --git a/tools/perf/arch/xtensa/Makefile b/tools/perf/arch/xtensa/Makefile
index 7fbca17..88c08ee 100644
--- a/tools/perf/arch/xtensa/Makefile
+++ b/tools/perf/arch/xtensa/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 ifndef NO_DWARF
 PERF_HAVE_DWARF_REGS := 1
 endif
diff --git a/tools/perf/arch/xtensa/util/Build b/tools/perf/arch/xtensa/util/Build
index 954e287..e813e61 100644
--- a/tools/perf/arch/xtensa/util/Build
+++ b/tools/perf/arch/xtensa/util/Build
@@ -1 +1 @@
-libperf-$(CONFIG_DWARF) += dwarf-regs.o
+perf-$(CONFIG_DWARF) += dwarf-regs.o
diff --git a/tools/perf/arch/xtensa/util/dwarf-regs.c b/tools/perf/arch/xtensa/util/dwarf-regs.c
index 4dba76b..12f5457 100644
--- a/tools/perf/arch/xtensa/util/dwarf-regs.c
+++ b/tools/perf/arch/xtensa/util/dwarf-regs.c
@@ -1,12 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Mapping of DWARF debug register numbers into register names.
  *
  * Copyright (c) 2015 Cadence Design Systems Inc.
- *
- * 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 <stddef.h>