!1651 Fix missing dealloc_dfx_cnt() during device unregister

Merge Pull Request from: @stinft 
 
https://gitee.com/openeuler/kernel/issues/I7PDHP 
 
Link:https://gitee.com/openeuler/kernel/pulls/1651

 

Reviewed-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>