dt-bindings: gpio: Convert altr,pio-1.0 to DT schema

Convert the altr,pio-1.0 binding to DT schema format. It's a
straight forward conversion.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250714202905.3012386-1-robh@kernel.org


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>