libhns: Fix reference to uninitialized cq pointer

For QPs which do not have an SQ, such as XRC TGT，the send_cq
pointer will not be initailized. Since the supported max_gs
will be 0 in this case, check it and return before referencing
the send_cq pointer.

Fixes: cbdf5e3 ("libhns: Reimplement verbs of post_send and post_recv for hip08 RoCE")
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>

providers/hns/hns_roce_u_hw_v2.c

@@ -1288,15 +1288,15 @@ int hns_roce_u_v2_post_send(struct ibv_qp *ibvqp, struct ibv_send_wr *wr,
 	sge_info.start_idx = qp->next_sge; /* start index of extend sge */
 
 	for (nreq = 0; wr; ++nreq, wr = wr->next) {
-		if (hns_roce_v2_wq_overflow(&qp->sq, nreq,
-					    to_hr_cq(qp->verbs_qp.qp.send_cq))) {
-			ret = ENOMEM;
+		if (wr->num_sge > (int)qp->sq.max_gs) {
+			ret = qp->sq.max_gs > 0 ? EINVAL : EOPNOTSUPP;
 			*bad_wr = wr;
 			goto out;
 		}
 
-		if (wr->num_sge > qp->sq.max_gs) {
-			ret = EINVAL;
+		if (hns_roce_v2_wq_overflow(&qp->sq, nreq,
+					    to_hr_cq(qp->verbs_qp.qp.send_cq))) {
+			ret = ENOMEM;
 			*bad_wr = wr;
 			goto out;
 		}