ARM: dts: lan966x: Enable network driver on pcb8291

The pcb8291 has 2 ports that are connected to the internal ports
of the switch. Enable them in DT.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
[claudiu.beznea: moved status ="okay" at the end for port0 and port1]
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220719201158.1696168-4-horatiu.vultur@microchip.com