IB/hns: Fix the bug of polling cq failed for loopback Qps

In hip06 SoC, RoCE driver creates 8 reserved loopback QPs to
ensure zero wqe when free mr. However, if the enabled phy
port number is less than 6, it will fail in polling cqe with
8 reserved loopback QPs.

In order to solve this problem, the number of loopback Qps
will be adjusted based on the number of enabled phy port.

Signed-off-by: Shaobo Xu <xushaobo2@huawei.com>
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>