gpio: ep93xx: Pass irqchip when adding gpiochip

We need to convert all old gpio irqchips to pass the irqchip
setup along when adding the gpio_chip. For more info see
drivers/gpio/TODO.

For chained irqchips this is a pretty straight-forward
conversion.

Cc: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Thierry Reding <treding@nvidia.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20190812130000.22252-1-linus.walleij@linaro.org