Remove duplicated code

internal/statements/associate.go

@@ -1,14 +0,0 @@
-// Copyright 2017 The Xorm Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package statements
-
-type cascadeMode int
-
-const (
-	cascadeCompitable cascadeMode = iota // load field beans with another SQL with no
-	cascadeEager                         // load field beans with another SQL
-	cascadeJoin                          // load field beans with join
-	cascadeLazy                          // don't load anything
-)