RDMA/hns: Add vendor_err info to error WC

ULP can get more error information of CQ through verbs instead of prints.

Link: https://lore.kernel.org/r/1624362836-11631-1-git-send-email-liweihang@huawei.com
Signed-off-by: Lang Cheng <chenglang@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>