Fix following problems about VLAN driver:

1. "VLAN Configuration” form crash after 'reconnect -r'
2. disconnect VLAN driver from the managed device will return EFI_NOT_FOUND
3. disconnect MNP driver from the managed device, VLAN driver couldn't be stopped.
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Ni, Ruiyu <ruiyu.ni@intel.com>
Reviewed-by: Gao, Liming <liming.gao@intel.com>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15174 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/Network/VlanConfigDxe/VlanConfigImpl.h

@@ -1,7 +1,7 @@
 /** @file
   Header file for driver binding protocol and HII config access protocol.
 
-Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2009 - 2014, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions
 of the BSD License which accompanies this distribution.  The full
@@ -282,8 +282,11 @@ InstallVlanConfigForm (
 
   @param[in, out]  PrivateData   Points to VLAN configuration private data.
 
+  @retval EFI_SUCCESS            HII Form has been uninstalled successfully.
+  @retval Others                 Other errors as indicated.
+
 **/
-VOID
+EFI_STATUS
 UninstallVlanConfigForm (
   IN OUT VLAN_CONFIG_PRIVATE_DATA    *PrivateData
   );