RDMA/cxgb3: Clean up signed check of unsigned variable

Q_FREECNT() returns the number of spaces free.  This should never be a
negative amount.  Also the num_wrs is an unsigned int so it can never
be less than zero.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/cxgb3/iwch_qp.c

@@ -371,7 +371,7 @@ int iwch_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 	}
 	num_wrs = Q_FREECNT(qhp->wq.sq_rptr, qhp->wq.sq_wptr,
 		  qhp->wq.sq_size_log2);
-	if (num_wrs <= 0) {
+	if (num_wrs == 0) {
 		spin_unlock_irqrestore(&qhp->lock, flag);
 		err = -ENOMEM;
 		goto out;
@@ -554,7 +554,7 @@ int iwch_bind_mw(struct ib_qp *qp,
 	}
 	num_wrs = Q_FREECNT(qhp->wq.sq_rptr, qhp->wq.sq_wptr,
 			    qhp->wq.sq_size_log2);
-	if ((num_wrs) <= 0) {
+	if (num_wrs == 0) {
 		spin_unlock_irqrestore(&qhp->lock, flag);
 		return -ENOMEM;
 	}