drivers: gpio: xlnx: Add support for versal2 PS/PMC GPIO

Add driver support for Versal Gen 2 PS/PMC GPIO controller by updating
the logic of bank index calculation.

This logic depends on "register" DT property to identify bank index
instead of depending on node instance ID as Versal Gen 2 GPIO banks
are not in sequential order as Zynqmp.

- Versal Gen 2 PS GPIO: Banks(0,3,4)
- Zynqmp PS GPIO: Banks(0,1,2,3,4,5)

Signed-off-by: Paul Alvin <alvin.paulp@amd.com>