net: dsa: microchip: use common irq routines for girq and pirq

The global port interrupt routines and individual ports interrupt
routines has similar implementation except the mask & status register
and number of nested irqs in them.  The mask & status register and
pointer to ksz_device is added to ksz_irq and uses the ksz_irq as
irq_chip_data.

Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>