x86: unify pmd_pfn

Impact: cleanup

Unify and demacro pmd_pfn.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index a7dbb05..532144c 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -510,6 +510,11 @@
 {
 	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
 }
+
+static inline unsigned long pmd_pfn(pmd_t pmd)
+{
+	return (pmd_val(pmd) & PTE_PFN_MASK) >> PAGE_SHIFT;
+}
 #endif	/* PAGETABLE_LEVELS > 2 */
 
 #if PAGETABLE_LEVELS > 3