Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull small x86 fixes from Peter Anvin:
 "A collection of very small fixes, mostly pure documentation."

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, doc: Document that bootloader ID 4 is used also by iPXE
  x86, doc: Add a formal bootloader ID for kexec-tools
  x86, 8042: Enable A20 using KBC to fix S3 resume on some MSI laptops