ionic: use new helper tcp_v6_gso_csum_prep

Use new helper tcp_v6_gso_csum_prep in additional network drivers.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Acked-by: NShannon Nelson <snelson@pensando.io>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_txrx.c

@@ -632,10 +632,7 @@ static int ionic_tx_tcp_pseudo_csum(struct sk_buff *skb)
 					   ip_hdr(skb)->daddr,
 					   0, IPPROTO_TCP, 0);
 	} else if (skb->protocol == cpu_to_be16(ETH_P_IPV6)) {
-		tcp_hdr(skb)->check =
-			~csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
-					 &ipv6_hdr(skb)->daddr,
-					 0, IPPROTO_TCP, 0);
+		tcp_v6_gso_csum_prep(skb);
 	}
 
 	return 0;