RDMA/hns: Assign zero for pkey_index of wc in hip08

Because pkey is fixed for hip08 RoCE, it needs to assign zero for
pkey_index of wc. otherwise, it will happen an error when establishing
connection by communication management mechanism.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Yixian Liu <liuyixian@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>