net: ethernet: ti: cpsw_new: populate netdev of_node

So that of_find_net_device_by_node() can find CPSW ports and other DSA
switches can be stacked downstream. Tested in conjunction with KSZ8873.

Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://patch.msgid.link/20250303074703.1758297-1-alexander.sverdlin@siemens.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ti/cpsw_new.c

@@ -1418,6 +1418,7 @@ static int cpsw_create_ports(struct cpsw_common *cpsw)
 		ndev->netdev_ops = &cpsw_netdev_ops;
 		ndev->ethtool_ops = &cpsw_ethtool_ops;
 		SET_NETDEV_DEV(ndev, dev);
+		ndev->dev.of_node = slave_data->slave_node;
 
 		if (!napi_ndev) {
 			/* CPSW Host port CPDMA interface is shared between