arm64: dts: mediatek: mt8183: align Google CROS EC PWM node name with dtschema

dtschema expects PWM node name to be a generic "pwm".  This also matches
Devicetree specification requirements about generic node names.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220214081916.162014-3-krzysztof.kozlowski@canonical.com


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