x86: unify pmd_page

Impact: cleanup

Unify and demacro pmd_page.

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 3789c05..38330d6 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -473,6 +473,11 @@
 	return (unsigned long)__va(pmd_val(pmd) & PTE_PFN_MASK);
 }
 
+static inline struct page *pmd_page(pmd_t pmd)
+{
+	return pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT);
+}
+
 #if PAGETABLE_LEVELS > 2
 static inline int pud_present(pud_t pud)
 {