net: ethernet: ti: am65-cpsw-nuss: populate netdev of_node

So that of_find_net_device_by_node() can find cpsw-nuss ports and other DSA
switches can be stacked downstream.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://lore.kernel.org/r/20240528075954.3608118-3-alexander.sverdlin@siemens.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -2703,6 +2703,7 @@ am65_cpsw_nuss_init_port_ndev(struct am65_cpsw_common *common, u32 port_idx)
 	mutex_init(&ndev_priv->mm_lock);
 	port->qos.link_speed = SPEED_UNKNOWN;
 	SET_NETDEV_DEV(port->ndev, dev);
+	port->ndev->dev.of_node = port->slave.port_np;
 
 	eth_hw_addr_set(port->ndev, port->slave.mac_addr);