regulator: max77802: Separate sections for nodes and properties

The optional "regulators" is a node and not a property so it should not
be in the "Optional properties" section but in an "Optional nodes" one.

Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>