ASoC: cs35l45: Add AMP Enable Switch control

The "AMP Enable Switch" is useful in systems with multiple
amplifiers connected to the same audio bus
but not all of them are needed for all use cases.

Signed-off-by: Vlad Karpovich <vkarpovi@opensource.cirrus.com>
Acked-by: Ricardo Rivera-Matos <rriveram@opensource.cirrus.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230831162042.471801-4-vkarpovi@opensource.cirrus.com


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