RDMA/hns: Only assign mtu if IB_QP_PATH_MTU bit is set

Only when the IB_QP_PATH_MTU flag of attr_mask is set
it is valid to assign the mtu field of qp context when
qp type is not GSI and UD.
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -2850,7 +2850,7 @@ static int modify_qp_init_to_rtr(struct ib_qp *ibqp,
 	if (ibqp->qp_type == IB_QPT_GSI || ibqp->qp_type == IB_QPT_UD)
 		roce_set_field(context->byte_24_mtu_tc, V2_QPC_BYTE_24_MTU_M,
 			       V2_QPC_BYTE_24_MTU_S, IB_MTU_4096);
-	else
+	else if (attr_mask & IB_QP_PATH_MTU)
 		roce_set_field(context->byte_24_mtu_tc, V2_QPC_BYTE_24_MTU_M,
 			       V2_QPC_BYTE_24_MTU_S, attr->path_mtu);