dt-bindings: gpio: Add Tegra234 support

Extend the existing Tegra186 GPIO controller device tree bindings with
support for the GPIO controller found on Tegra234. The number of pins is
slightly different, but the programming model remains the same.

Signed-off-by: Prathamesh Shete <pshete@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
[treding@nvidia.com: update device tree bindings]
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>