qlcnic: additional driver statistics

Added additional driver statistics to track errors in rcv/tx path.

Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/qlcnic/qlcnic_main.c b/drivers/net/qlcnic/qlcnic_main.c
index e4fd5dc..5845dc0 100644
--- a/drivers/net/qlcnic/qlcnic_main.c
+++ b/drivers/net/qlcnic/qlcnic_main.c
@@ -1589,8 +1589,10 @@
 
 	pdev = adapter->pdev;
 
-	if (qlcnic_map_tx_skb(pdev, skb, pbuf))
+	if (qlcnic_map_tx_skb(pdev, skb, pbuf)) {
+		adapter->stats.tx_dma_map_error++;
 		goto drop_packet;
+	}
 
 	pbuf->skb = skb;
 	pbuf->frag_count = frag_count;