RDMA/hns: Fix missing dealloc_dfx_cnt() during device unregister

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7PDHP



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The function hns_roce_dealloc_dfx_cnt() was omitted while
uploading "RDMA/hns: Add dfx cnt stats".

This patch fixes it.

Fixes: d5a4ca75 ("RDMA/hns: Add dfx cnt stats")
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
(cherry picked from commit 0e452e80)