Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/scripts/Makefile.kcov b/scripts/Makefile.kcov
index 3d61c4b..52b1133 100644
--- a/scripts/Makefile.kcov
+++ b/scripts/Makefile.kcov
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 ifdef CONFIG_KCOV
 
 kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC)	+= -fsanitize-coverage=trace-pc