net: virtio_net: add get_rxrings ethtool callback for RX ring queries

Replace the existing virtnet_get_rxnfc callback with a dedicated
virtnet_get_rxrings implementation to provide the number of RX rings
directly via the new ethtool_ops get_rx_ring_count pointer.

This simplifies the RX ring count retrieval and aligns virtio_net with
the new ethtool API for querying RX ring parameters.

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20250917-gxrings-v4-8-dae520e2e1cb@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: leitao

drivers/net/virtio_net.c

@@ -5609,20 +5609,11 @@ static int virtnet_set_rxfh(struct net_device *dev,
 	return 0;
 }
 
-static int virtnet_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info, u32 *rule_locs)
+static u32 virtnet_get_rx_ring_count(struct net_device *dev)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
-	int rc = 0;
 
-	switch (info->cmd) {
-	case ETHTOOL_GRXRINGS:
-		info->data = vi->curr_queue_pairs;
-		break;
-	default:
-		rc = -EOPNOTSUPP;
-	}
-
-	return rc;
+	return vi->curr_queue_pairs;
 }
 
 static const struct ethtool_ops virtnet_ethtool_ops = {
@@ -5650,7 +5641,7 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
 	.set_rxfh = virtnet_set_rxfh,
 	.get_rxfh_fields = virtnet_get_hashflow,
 	.set_rxfh_fields = virtnet_set_hashflow,
-	.get_rxnfc = virtnet_get_rxnfc,
+	.get_rx_ring_count = virtnet_get_rx_ring_count,
 };
 
 static void virtnet_get_queue_stats_rx(struct net_device *dev, int i,