gpio: ep93xx: convert driver to DT

gpio: ep93xx: convert driver to DT

This converts ep93xx SOC gpio into device tree driver:
- dropped banks and legacy defines
- split AB IRQ and make it shared

We are relying on IRQ number information A, B ports have single shared
IRQ, while F port have dedicated IRQ for each line.

Also we had to split single ep93xx platform_device into multiple, one
for each port, without this we can't do a full working transition from
legacy platform code into device tree capable:

- all GPIO_LOOKUP were change to match new chip namings
- add lookup table for leds

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>