regulator: dt-bindings: maxim,max14577: Convert to dtschema

Convert the regulator bindings of Maxim MAX14577/MAX77835 MUIC to DT
schema format.  The existing bindings were defined in
../bindings/mfd/max14577.txt.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220215074759.29402-3-krzysztof.kozlowski@canonical.com