ARM: dts: BCM53573: Add Ethernet interfaces links

BCM53573 has 2 Ethernet interfaces each connected to one of switch ports
in the default design. They both use fixed links.

An exception are Luxul XAP devices that have switch replaced by a single
PHY.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20230724101227.5420-1-zajec5@gmail.com


Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>