RDMA/hns: Add mtr support for mixed multihop addressing

Currently, the MTT(memory translate table) design required a buffer
space must has the same hopnum, but the hip08 hw can support mixed
hopnum config in a buffer space.

This patch adds the MTR(memory translate region) design for supporting
mixed multihop.

Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>