ARM: dts: lan966x: add support for pcb8309

Add basic support for pcb8309. It is similar with pcb8291 with one big
difference that is having 2 SFP cages. Therefore it has 4 network ports.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220722131836.2377720-3-horatiu.vultur@microchip.com