RDMA/cxgb4: Fix missing error code in create_qp()

The error code is missing in this code scenario so 0 will be returned. Add
the error code '-EINVAL' to the return value 'ret'.

Eliminates the follow smatch warning:

drivers/infiniband/hw/cxgb4/qp.c:298 create_qp() warn: missing error code 'ret'.

Link: https://lore.kernel.org/r/1622545669-20625-1-git-send-email-jiapeng.chong@linux.alibaba.comReported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/cxgb4/qp.c

@@ -295,6 +295,7 @@ static int create_qp(struct c4iw_rdev *rdev, struct t4_wq *wq,
 	if (user && (!wq->sq.bar2_pa || (need_rq && !wq->rq.bar2_pa))) {
 		pr_warn("%s: sqid %u or rqid %u not in BAR2 range\n",
 			pci_name(rdev->lldi.pdev), wq->sq.qid, wq->rq.qid);
+		ret = -EINVAL;
 		goto free_dma;
 	}