移除用户全名与以往用户名不一致的限制。

Log: 修复用户全名与以往用户名相同时提示无法创建用户的问题。
Bug: https://pms.uniontech.com/zentao/bug-view-49731.html
Change-Id: Ic1633704e5fa327fe2e2865ac1c72f399a48b672
Reviewed-on: http://gerrit.uniontech.com/c/dde-control-center/+/6453
Reviewed-by: lvpeilong <lvpeilong@uniontech.com>
Reviewed-by: <mailman@uniontech.com>
Tested-by: <mailman@uniontech.com>