x86: Fix included-by file reference comments

Adjust the paths for files that are including verify_cpu.S.

Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Kees Cook <kees.cook@canonical.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
LKML-Reference: <1289931004-16066-1-git-send-email-kees.cook@canonical.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>