RDMA/hns: Fix error code of CMD

The error code is fixed to EIO when CMD fails to excute. This patch
converts the error status reported by firmware to linux errno.

Fixes: a04ff739

 ("RDMA/hns: Add command queue support for hip08 RoCE driver")
Link: https://lore.kernel.org/r/20221126102911.2921820-6-xuhaoyue1@hisilicon.com
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Haoyue Xu <xuhaoyue1@hisilicon.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>