RDMA/hns: Reorganize process of setting HEM

Encapsulate configuring GMV base address and other type of HEM table into
two separate functions to make process of setting HEM clearer.

Link: https://lore.kernel.org/r/1616815294-13434-5-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@nvidia.com>