[TG3]: fixup tot_len calculation

Turning struct iphdr::tot_len into __be16 added sparse warning.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -3651,7 +3651,7 @@ static int tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			       TXD_FLAG_CPU_POST_DMA);
 
 		skb->nh.iph->check = 0;
-		skb->nh.iph->tot_len = ntohs(mss + ip_tcp_len + tcp_opt_len);
+		skb->nh.iph->tot_len = htons(mss + ip_tcp_len + tcp_opt_len);
 		if (tp->tg3_flags2 & TG3_FLG2_HW_TSO) {
 			skb->h.th->check = 0;
 			base_flags &= ~TXD_FLAG_TCPUDP_CSUM;