ASoC: dt-bindings: max98396: Document data monitor properties

This device features a data monitor that puts the device in software reset
upon a configurable set of events.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220826085927.2336224-1-daniel@zonque.org
Signed-off-by: Mark Brown <broonie@kernel.org>