regulator: dt-bindings: maxim,max8997: convert to dtschema

Convert the Maxim MAX8997 PMIC bindings to DT schema format.  Extend the
examples with additional one copied from kernel's exynos4210-origen.dts.
Also the binding descriptions are copied from old file, so license
entire work under GPL-2.0.

This also adds previously undocumented 32 kHz clock output modelled as
regulators.

Signed-off-by: Krzysztof Kozlowski <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: krzk