!4990 vt: fix memory overlapping when deleting chars in the buffer

Merge Pull Request from: @ci-robot 
 
PR sync from: Yi Yang <yiyang13@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/OSA3EKI3AKV6I72J5GIDGIZCU3XZF654/ 
 
https://gitee.com/src-openeuler/kernel/issues/I95ATI 
 
Link:https://gitee.com/openeuler/kernel/pulls/4990

 

Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Reviewed-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>