ASoC: cs35l56: Allow factory calibration through ALSA controls

ASoC: cs35l56: Allow factory calibration through ALSA controls

Add support for using ALSA controls to trigger a factory calibration.
This is protected by a new Kconfig option so that it is only available
if explicitly enabled in the kernel. By default it is not enabled.

Factory calibration is normally done through debugfs files.
Google have requested that factory calibration can be performed by
repair shops. These repair shops only have access to the standard
"user" kernel, which does not include debugfs.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20260325170841.1405368-3-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>