RDMA/hns: Configure BT BA and BT attribute for the contexts in hip08

BT is used to retrieve the addresses of the contexts(QPC/MPT/CQC/SRQC)
in memory. In order to support multi hop addressing for the contexts,
the BT BA should be configured by mailbox, and the BT attribution will
be set by command.

This patch is to configure the BT BA and BT attribution 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>