ARM: dts: mediatek: align gpio-key node names with dtschema

The node names should be generic and DT schema expects certain pattern
(e.g. with key/button/switch).

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220616005333.18491-18-krzysztof.kozlowski@linaro.org


Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>