RDMA/hns: Support hns HW stats

driver inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6GSZL



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Support query hns HW stats to help debugging several issues.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Reviewed-by: Yangyang Li <liyangyang20@huawei.com>