x86, realmode: Move reboot_32.S to unified realmode code

Migrated reboot_32.S from x86_trampoline to the real-mode
blob.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-5-git-send-email-jarkko.sakkinen@intel.com


Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>