net: ti: icssg_prueth: populate netdev of_node

Allow of_find_net_device_by_node() to find icssg_prueth ports and make
the individual ports' of_nodes available in sysfs.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: MD Danish Anwar <danishanwar@ti.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20240807121215.3178964-1-matthias.schiffer@ew.tq-group.com


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