x86: unify pgd_page

Impact: cleanup

Unify and demacro pgd_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 a871ae5..c1a36dd 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -495,6 +495,11 @@
 {
 	return (unsigned long)__va((unsigned long)pgd_val(pgd) & PTE_PFN_MASK);
 }
+
+static inline struct page *pgd_page(pgd_t pgd)
+{
+	return pfn_to_page(pgd_val(pgd) >> PAGE_SHIFT);
+}
 #endif	/* PAGETABLE_LEVELS > 3 */
 
 #endif	/* __ASSEMBLY__ */