!7964 v2 vt: fix unicode buffer corruption when deleting characters

Merge Pull Request from: @ci-robot 
 
PR sync from: Xiang Yang <xiangyang3@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/DLHVHBLJL6LCNDSWK6OCMPEFWWWCXPJT/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9Q994 
 
Link:https://gitee.com/openeuler/kernel/pulls/7964

 

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