IB/hns: Update the rq head when modify qp state

The rq head in qpc was zero will miss the rq wqes which
have be sent, so here we should take the real value.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Reviewed-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>