IB/hfi1: Correct defered count after processing qp_wait_list

The qp_wait_list processing leaves the defered ack count
at its prior value.

This can result in a premature send of an ack.

Fixed by unconditionally reseting the defered ack count
in hfi1_send_rc_ack().

Fixes: Commit 7c091e5c ("staging/rdma/hfi1: add ACK coalescing logic")
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/rc.c

@@ -853,6 +853,10 @@ void hfi1_send_rc_ack(struct hfi1_ctxtdata *rcd, struct rvt_qp *qp,
 	struct ib_header hdr;
 	struct ib_other_headers *ohdr;
 	unsigned long flags;
+	struct hfi1_qp_priv *priv = qp->priv;
+
+	/* clear the defer count */
+	priv->r_adefered = 0;
 
 	/* Don't send ACK or NAK if a RDMA read or atomic is pending. */
 	if (qp->s_flags & RVT_S_RESP_PENDING)