RDMA/core: Fix return error value in _ib_modify_qp() to negative

The error codes in _ib_modify_qp() are supposed to be negative errno.

Fixes: 7a5c938b ("IB/core: Check for rdma_protocol_ib only after validating port_num")
Link: https://lore.kernel.org/r/1595645787-20375-1-git-send-email-liheng40@huawei.comReported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Li Heng <liheng40@huawei.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/verbs.c

@@ -1710,7 +1710,7 @@ static int _ib_modify_qp(struct ib_qp *qp, struct ib_qp_attr *attr,
 		if (!(rdma_protocol_ib(qp->device,
 				       attr->alt_ah_attr.port_num) &&
 		      rdma_protocol_ib(qp->device, port))) {
-			ret = EINVAL;
+			ret = -EINVAL;
 			goto out;
 		}
 	}