regulator: dt-bindings: Describe Maxim MAX20411

Add binding for the Maxim MAX20411 step-down DC-DC converter.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Link: https://lore.kernel.org/r/20230124184440.1421074-2-quic_bjorande@quicinc.com


Signed-off-by: Mark Brown <broonie@kernel.org>