IB/srpt: Convert a warning into a debug message

At least when running the ib_srpt driver on top of the rdma_rxe
driver it is easy to trigger a zero-length write completion in
the CH_DISCONNECTED state. Hence make the message that reports
this less noisy.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -875,7 +875,8 @@ static void srpt_zerolength_write_done(struct ib_cq *cq, struct ib_wc *wc)
 		if (srpt_set_ch_state(ch, CH_DISCONNECTED))
 			schedule_work(&ch->release_work);
 		else
-			WARN_ONCE(1, "%s-%d\n", ch->sess_name, ch->qp->qp_num);
+			pr_debug("%s-%d: already disconnected.\n",
+				 ch->sess_name, ch->qp->qp_num);
 	}
 }