Fix a bug in Mtftp6 retransmission mechanism of the ACK.
Signed-off-by: Ari Zigler <ariz@mellanox.com>
Reviewed-by: Ouyang Qian <qian.ouyang@intel.com> 
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14450 6f19259b-4bc3-4df7-8a09-765794883524