RDMA/hns: Delete the not-used lines

Delete the assignment of srq->ibsrq.ext.xrc.srq_num, beacause this
value is not used.

Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Link: https://lore.kernel.org/r/1566393276-42555-9-git-send-email-oulijun@huawei.com


Signed-off-by: Doug Ledford <dledford@redhat.com>