gpio: ep93xx: split device in multiple

Prepare ep93xx SOC gpio to convert 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.

Signed-off-by: Nikita Shubin <nikita.shubin@maquefel.me>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>