dt-bindings: gpio: Minor whitespace cleanup in example

The DTS code coding style expects exactly one space around '='
character.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Acked-by: Yixun Lan <dlan@gentoo.org>
Link: https://lore.kernel.org/r/20250821083213.46642-2-krzysztof.kozlowski@linaro.org


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