gpio: tegra: Convert to gpio_irq_chip

Convert the Tegra GPIO driver to use the gpio_irq_chip infrastructure.
This allows a bit of boiler plate to be removed and while at it enables
support for hierarchical domains, which is useful to support PMC wake
events on Tegra210 and earlier.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>