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>