x86: unify pgtable accessors which use, #2

based on:

 Subject: x86: unify pgtable accessors which use supported_pte_mask
 From: Jeremy Fitzhardinge <jeremy@goop.org>

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