ALSA: doc: cs35l56: Add information about Cirrus Logic CS35L54/56/57

Add documentation for the Cirrus Logic CS35L54/56/57 amps, which are
all managed by the cs35l56 drivers.

The aim and scope of this documentation is to provide troubleshooting
information for end-users.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20250108141045.1032-1-rf@opensource.cirrus.com


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