x86: unify pgd_present

Impact: cleanup

Unify and demacro pgd_present.

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 c117b28..339e49a 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -452,6 +452,13 @@
 }
 #endif	/* PAGETABLE_LEVELS > 2 */
 
+#if PAGETABLE_LEVELS > 3
+static inline int pgd_present(pgd_t pgd)
+{
+	return pgd_val(pgd) & _PAGE_PRESENT;
+}
+#endif	/* PAGETABLE_LEVELS > 3 */
+
 #endif	/* __ASSEMBLY__ */
 
 #ifdef CONFIG_X86_32