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/VlanConfigDriver.c

@@ -1,7 +1,7 @@
 /** @file
   The driver binding for VLAN configuration module.
 
-Copyright (c) 2009, 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
@@ -275,10 +275,13 @@ VlanConfigDriverBindingStop (
   }
   ASSERT (PrivateData->Signature == VLAN_CONFIG_PRIVATE_DATA_SIGNATURE);
 
-  //
-  // Uninstall VLAN configuration Form
-  //
-  UninstallVlanConfigForm (PrivateData);
+  if (NumberOfChildren != 0) {
+    if (NumberOfChildren != 1 || ChildHandleBuffer[0] != PrivateData->DriverHandle) {
+      return EFI_DEVICE_ERROR;
+    }
+    
+    return UninstallVlanConfigForm (PrivateData);
+  }
 
   //
   // Uninstall the private GUID