Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c
index c16c182..aa075d8 100644
--- a/arch/arm/boot/compressed/decompress.c
+++ b/arch/arm/boot/compressed/decompress.c
@@ -32,6 +32,7 @@
 extern char * strstr(const char * s1, const char *s2);
 extern size_t strlen(const char *s);
 extern int memcmp(const void *cs, const void *ct, size_t count);
+extern char * strchrnul(const char *, int);
 
 #ifdef CONFIG_KERNEL_GZIP
 #include "../../../../lib/decompress_inflate.c"