x86: page.h: move and unify types for pagetable entry, #1

based on:

 Subject: x86: page.h: move and unify types for pagetable entry
 From: Jeremy Fitzhardinge <jeremy@goop.org>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>