RDMA/hns: Simplify process related to poll cq

Set hns_roce_v2_cq_set_ci to inline type and remove unnecessary
next_cqe_sw_v2().

Link: https://lore.kernel.org/r/1590152579-32364-4-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@mellanox.com>