Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/initrd.h b/include/linux/initrd.h
index 84b4230..d77fe34 100644
--- a/include/linux/initrd.h
+++ b/include/linux/initrd.h
@@ -21,4 +21,10 @@
 extern unsigned long initrd_start, initrd_end;
 extern void free_initrd_mem(unsigned long, unsigned long);
 
+extern phys_addr_t phys_initrd_start;
+extern unsigned long phys_initrd_size;
+
 extern unsigned int real_root_dev;
+
+extern char __initramfs_start[];
+extern unsigned long __initramfs_size;