qeth: add statistics for tx csum

Add statistics counter for software tx checksumming.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 0dcc036..fea50bd 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -2711,8 +2711,11 @@
 	}
 
 	if ((large_send == QETH_LARGE_SEND_NO) &&
-	    (new_skb->ip_summed == CHECKSUM_PARTIAL))
+	    (new_skb->ip_summed == CHECKSUM_PARTIAL)) {
 		qeth_tx_csum(new_skb);
+		if (card->options.performance_stats)
+			card->perf_stats.tx_csum++;
+	}
 
 	if (card->info.type != QETH_CARD_TYPE_IQD)
 		rc = qeth_do_send_packet(card, queue, new_skb, hdr,