ASoC: dt-bindings: cirrus,cs35l41: Document CS35l41 shared boost

Describe the properties used for shared boost configuration.
Based on David Rhodes shared boost patches.

Signed-off-by: Lucas Tanure <lucas.tanure@collabora.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: David Rhodes <david.rhodes@cirrus.com>
Link: https://lore.kernel.org/r/20230223084324.9076-5-lucas.tanure@collabora.com


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