RDMA/hns: Add support for addressing when hopnum is 0

driver inclusion
category: bugfix
bugzilla: NA
CVE: NA

Wraps the public logic as 3 functions: hns_roce_mtr_create(),
hns_roce_mtr_destroy() and hns_roce_mtr_map() to support hopnum ranges from
0 to 3. In addition, makes the mtr interfaces easier to use.
Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Shunfeng Yang <yangshunfeng2@huawei.com>
Reviewed-by: chunzhi hu <huchunzhi@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>