RDMA/hns: Optimize SRQ buffer size calculating process

Optimize the SRQ's WQE buffer parameters calculating process to make the
codes more readable by using new functions about multi-hop addressing to
calculating capabilities of SRQ.

Link: https://lore.kernel.org/r/1588071823-40200-6-git-send-email-liweihang@huawei.com


Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>