NTB: Rate limit ntb_qp_link_work

When the ntb transport is connecting and waiting for the peer, the debug
console receives lots of debug level messages about the remote qp link
status being down.  Rate limit those messages.
Signed-off-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

drivers/ntb/ntb_transport.c

@@ -850,7 +850,7 @@ static void ntb_qp_link_work(struct work_struct *work)
 
 	/* query remote spad for qp ready bits */
 	ntb_peer_spad_read(nt->ndev, QP_LINKS);
-	dev_dbg(&pdev->dev, "Remote QP link status = %x\n", val);
+	dev_dbg_ratelimited(&pdev->dev, "Remote QP link status = %x\n", val);
 
 	/* See if the remote side is up */
 	if (val & BIT(qp->qp_num)) {