x86 PAT: fix mmap() of holes

do not return a -EINVAL when mmap()-ing PCI holes.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>

arch/x86/mm/pageattr.c

@@ -542,7 +542,7 @@ static int __change_page_attr(struct cpa_data *cpa, int primary)
 repeat:
 	kpte = lookup_address(address, &level);
 	if (!kpte)
-		return primary ? -EINVAL : 0;
+		return 0;
 
 	old_pte = *kpte;
 	if (!pte_val(old_pte)) {