RDMA/hns: Remove redundant operations on CMDQ

CMDQ works serially, after each successful transmission, the head and tail
pointers will be equal, so there is no need to check whether the queue is
full. At the same time, since the descriptor of each transmission is new,
there is no need to perform a cleanup operation. Then, the field named
next_to_clean in structure hns_roce_v2_cmq_ring is redundant.

Fixes: a04ff739 ("RDMA/hns: Add command queue support for hip08 RoCE driver")
Link: https://lore.kernel.org/r/1612688143-28226-4-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>