Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/microblaze/Kconfig.debug b/arch/microblaze/Kconfig.debug
index dc2e3c4..865527a 100644
--- a/arch/microblaze/Kconfig.debug
+++ b/arch/microblaze/Kconfig.debug
@@ -1,5 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
 # For a description of the syntax of this configuration file,
-# see Documentation/kbuild/kconfig-language.txt.
+# see Documentation/kbuild/kconfig-language.rst.
 
 config TRACE_IRQFLAGS_SUPPORT
 	def_bool y