RDMA/rtrs: Check device max_qp_wr limit when create QP

Currently we only check device max_qp_wr limit for IO connection, but not
for service connection. We should check for both.

So save the max_qp_wr device limit in wr_limit, and use it for both IO
connections and service connections.

While at it, also remove an outdated comments.

Link: https://lore.kernel.org/r/20210614090337.29557-6-jinpu.wang@ionos.com
Suggested-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>