ASoC: cs35l56: Create debugfs files for factory calibration

ASoC: cs35l56: Create debugfs files for factory calibration

Create debugfs files that can be used to perform factory calibration.

During manufacture, the production line must perform a factory calibration
of the amps. This patch adds this functionality via debugfs files.

As this is only needed during manufacture, there is no need for this to be
available in a normal system so a Kconfig item has been added to enable
this. The new Kconfig option is inside a sub-menu because items do not
group and indent if the parent is invisible or there are multiple parent
dependencies. Anyway the sub-menu reduces the clutter.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20251021105022.1013685-5-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>