Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/elfcore.c b/kernel/elfcore.c
index fc482c8..57fb4dc 100644
--- a/kernel/elfcore.c
+++ b/kernel/elfcore.c
@@ -3,6 +3,7 @@
 #include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/binfmts.h>
+#include <linux/elfcore.h>
 
 Elf_Half __weak elf_core_extra_phdrs(void)
 {