pinctrl: bcm2835: 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. The BCM2835 has multiple parents so let's
exploit the new facility in the GPIO_IRQCHIP to actually
deal with multiple parents.

Cc: Eric Anholt <eric@anholt.net>
Cc: Thierry Reding <treding@nvidia.com>
[Rebased on changes in the pinctrl tree]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/20190812062729.1892-1-linus.walleij@linaro.org