Devicetree binding documentation for CS35L41 driver

CS35L41 is a 11-V Boosted Mono Class D Amplifier with
DSP Speaker Protection and Equalization
Signed-off-by: David Rhodes <drhodes@opensource.cirrus.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210907225719.2018115-3-drhodes@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>