net: dsa: microchip: Use dynamic irq offset

net: dsa: microchip: Use dynamic irq offset

The PTP irq_chip operations use an hardcoded IRQ offset in the bit
logic. This IRQ offset isn't the same on KSZ8463 than on others switches
so it can't use the irq_chip operations.

Convey the interrupt bit offset through a new attribute in struct ksz_irq

Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
Link: https://patch.msgid.link/20260105-ksz-rework-v1-2-a68df7f57375@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>