Avoid some dead code and cleanup in relaxng.c

https://bugzilla.gnome.org/show_bug.cgi?id=705388

Code needed a bit of cleanup
diff --git a/relaxng.c b/relaxng.c
index 370e314..bfaceb7 100644
--- a/relaxng.c
+++ b/relaxng.c
@@ -2595,13 +2595,10 @@
     }
     ret = xmlSchemaValPredefTypeNode(typ, value2, &res2, ctxt2);
     if (ret != 0) {
-	if ((comp1 == NULL) && (res1 != NULL))
+	if (res1 != (xmlSchemaValPtr) comp1)
 	    xmlSchemaFreeValue(res1);
         return (-1);
     }
-    if (res1 == NULL) {
-        return (-1);
-    }
     ret = xmlSchemaCompareValues(res1, res2);
     if (res1 != (xmlSchemaValPtr) comp1)
         xmlSchemaFreeValue(res1);