RDMA/hns: Add the interfaces to support multi hop addressing for the contexts in hip08

The contexts (QPC/MTPT/CQC/SRQC) in hip08 can support multi hop
addressing. The address of context can be retrieved by the
BT (Base Address Table) with multi hop addressing. The first hop
BT BA can be retrieved from the RAM in the chip by the bt_idx and
bt_num.

This patch is to add the interfaces in HEM to support multi hop
addressing for the contexts.

Signed-off-by: Shaobo Xu <xushaobo2@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>