cxgb4: Fix tx flit calculation

In commit 0aac3f56 ("cxgb4: Add comment for calculate tx flits
and sge length code") introduced a regression where tx flit calculation
is going wrong, which can lead to data corruption, hang, stall and
write-combining failure. Fixing it.
Signed-off-by: NHariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/sge.c

@@ -807,7 +807,7 @@ static inline unsigned int calc_tx_flits(const struct sk_buff *skb)
 	 * message or, if we're doing a Large Send Offload, an LSO CPL message
 	 * with an embedded TX Packet Write CPL message.
 	 */
-	flits = sgl_len(skb_shinfo(skb)->nr_frags + 1) + 4;
+	flits = sgl_len(skb_shinfo(skb)->nr_frags + 1);
 	if (skb_shinfo(skb)->gso_size)
 		flits += (sizeof(struct fw_eth_tx_pkt_wr) +
 			  sizeof(struct cpl_tx_pkt_lso_core) +