net: bcmgenet: correct per TX/RX ring statistics

The change to track net_device_stats per ring to better support SMP
missed updating the rx_dropped member.

The ndo_get_stats method is also needed to combine the results for
ethtool statistics (-S) before filling in the ethtool structure.

Fixes: 37a30b43 ("net: bcmgenet: Track per TX/RX rings statistics")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/genet/bcmgenet.c

@@ -934,6 +934,8 @@ static void bcmgenet_get_ethtool_stats(struct net_device *dev,
 	if (netif_running(dev))
 		bcmgenet_update_mib_counters(priv);
 
+	dev->netdev_ops->ndo_get_stats(dev);
+
 	for (i = 0; i < BCMGENET_STATS_LEN; i++) {
 		const struct bcmgenet_stats *s;
 		char *p;
@@ -3156,6 +3158,7 @@ static struct net_device_stats *bcmgenet_get_stats(struct net_device *dev)
 	dev->stats.rx_packets = rx_packets;
 	dev->stats.rx_errors = rx_errors;
 	dev->stats.rx_missed_errors = rx_errors;
+	dev->stats.rx_dropped = rx_dropped;
 	return &dev->stats;
 }