ARM: dts: lan966x: Fix the interrupt number for internal PHYs

According to the datasheet the interrupts for internal PHYs are
80 and 81.

Fixes: 6ad69e07 ("ARM: dts: lan966x: add MIIM nodes")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220912192629.461452-1-horatiu.vultur@microchip.com