dt-bindings: pinctrl: nuvoton,wpcm450-pinctrl: align key node name

gpio-keys schema requires keys to have more generic name.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220616005333.18491-4-krzysztof.kozlowski@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>