RDMA/iw_cxgb4: Fix the unchecked ep dereference

The patch 944661dd: "RDMA/iw_cxgb4: atomically lookup ep and get a
reference" from May 6, 2016, leads to the following Smatch complaint:

    drivers/infiniband/hw/cxgb4/cm.c:2953 terminate()
    error: we previously assumed 'ep' could be null (see line 2945)

Fixes: 944661dd ("RDMA/iw_cxgb4: atomically lookup ep and get a reference")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Raju Rangoju <rajur@chelsio.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/cxgb4/cm.c

@@ -2942,15 +2942,18 @@ static int terminate(struct c4iw_dev *dev, struct sk_buff *skb)
 
 	ep = get_ep_from_tid(dev, tid);
 
-	if (ep && ep->com.qp) {
-		pr_warn("TERM received tid %u qpid %u\n",
-			tid, ep->com.qp->wq.sq.qid);
-		attrs.next_state = C4IW_QP_STATE_TERMINATE;
-		c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
-			       C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
+	if (ep) {
+		if (ep->com.qp) {
+			pr_warn("TERM received tid %u qpid %u\n", tid,
+				ep->com.qp->wq.sq.qid);
+			attrs.next_state = C4IW_QP_STATE_TERMINATE;
+			c4iw_modify_qp(ep->com.qp->rhp, ep->com.qp,
+				       C4IW_QP_ATTR_NEXT_STATE, &attrs, 1);
+		}
+
+		c4iw_put_ep(&ep->com);
 	} else
 		pr_warn("TERM received tid %u no ep/qp\n", tid);
-	c4iw_put_ep(&ep->com);
 
 	return 0;
 }