Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index ae13bc9..ed8ec01 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -46,6 +46,9 @@
 
 extern void reserve_standard_io_resources(void);
 extern void i386_reserve_resources(void);
+extern unsigned long __startup_64(unsigned long physaddr, struct boot_params *bp);
+extern unsigned long __startup_secondary_64(void);
+extern int early_make_pgtable(unsigned long address);
 
 #ifdef CONFIG_X86_INTEL_MID
 extern void x86_intel_mid_early_setup(void);