net: ethernet: ti: am65-cpsw-nuss: rename phy_node -> port_np

Rename phy_node to port_np to better reflect what it actually is,
because the new phylink API takes netdev node (or DSA port node),
and resolves the phandle internally.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://lore.kernel.org/r/20240528075954.3608118-2-alexander.sverdlin@siemens.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>