bnxt_en: Implement xmit_more.

Do not write the TX doorbell if skb->xmit_more is set unless the TX
queue is full.
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -463,13 +463,17 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	prod = NEXT_TX(prod);
 	txr->tx_prod = prod;
 
-	bnxt_db_write(bp, txr->tx_doorbell, DB_KEY_TX | prod);
+	if (!skb->xmit_more)
+		bnxt_db_write(bp, txr->tx_doorbell, DB_KEY_TX | prod);
 
 tx_done:
 
 	mmiowb();
 
 	if (unlikely(bnxt_tx_avail(bp, txr) <= MAX_SKB_FRAGS + 1)) {
+		if (skb->xmit_more && !tx_buf->is_push)
+			bnxt_db_write(bp, txr->tx_doorbell, DB_KEY_TX | prod);
+
 		netif_tx_stop_queue(txq);
 
 		/* netif_tx_stop_queue() must be done before checking