ARM: dts: lan966x: Add interrupt support for PHYs on pcb8290

Add interrupt support for the PHYs found on pcb8290. They are all
sharing the same interrupt line towards lan966x.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220915064112.1935051-1-horatiu.vultur@microchip.com