Fix issue that TCP server will not response to SYN packet from TCP client in TCP6 module.

Signed-off-by: Ye Ting <ting.ye@intel.com>
Reviewed-by: Ouyang Qian <qian.ouyang@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13606 6f19259b-4bc3-4df7-8a09-765794883524

NetworkPkg/TcpDxe/TcpIo.c

@@ -1,7 +1,7 @@
 /** @file
   Implementation of I/O interfaces between TCP and IpIoLib.
 
-  Copyright (c) 2009 - 2010, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2009 - 2012, 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
@@ -112,7 +112,9 @@ TcpSendIpPacket (
       // It's IPv6 and this TCP segment belongs to a solid TCB, in such case
       // the destination address can't be overridden, so reset the Dest to NULL.
       //
-      Dest = NULL;
+      if (!Tcb->RemoteIpZero) {
+        Dest = NULL;
+      }
     }
   }