IB/hns: Fix the bug with wild pointer when destroy rc qp

When destroyed rc qp, the hr_qp will be used after freed. This patch
will fix it.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>