dt-bindings: leds: skyworks,aat1290: convert to dtschema

Convert the Skyworks Solutions, Inc. AAT1290 Current Regulator bindings
to DT Schema.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220721160611.250274-1-krzysztof.kozlowski@linaro.org