RDMA/hns: Remove the unused parameter "op_modifier" in mailbox

The parameter "op_modifier" is only used for HIP06. It is useless for HIP08
and later versions. After removing HIP06, this parameter is no longer used,
so remove it.

Link: https://lore.kernel.org/r/20220302064830.61706-2-liangwenpeng@huawei.com


Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Haoyue Xu <xuhaoyue1@hisilicon.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>