dt-bindings: pwm: marvell,berlin-pwm: Convert from txt to yaml

Formalize the binding for marvell,berlin-pwm devices and make them
automatically checkable. No change to the binding intended.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20241029160837.590199-2-u.kleine-koenig@baylibre.com


Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>