dt-bindings: leds: irled: pwm-ir-tx: convert to DT schema

Convert the PWM IR LED bindings to DT schema.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221204104323.117974-2-krzysztof.kozlowski@linaro.org


Signed-off-by: Rob Herring <robh@kernel.org>