dt-bindings: gpio: gpio_oxnas: remove obsolete bindings

Due to lack of maintenance and stall of development for a few years now,
and since no new features will ever be added upstream, remove the
OX810 and OX820 gpio bindings.

Acked-by: Krzysztof Kozlowski <[email protected]>
Acked-by: Linus Walleij <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Acked-by: Daniel Golle <[email protected]>
Acked-by: Bartosz Golaszewski <[email protected]>
Signed-off-by: Neil Armstrong <[email protected]>
Link: https://lore.kernel.org/r/20230814-topic-oxnas-upstream-remove-v3-3-04a0c5cdda52@linaro.org
Signed-off-by: Linus Walleij <[email protected]>

Author: superna9999