ASoC: cs35l56: Support for reading speaker ID from on-chip GPIOs

ASoC: cs35l56: Support for reading speaker ID from on-chip GPIOs

Add support for using the state of pins on the amplifier to indicate
the type of speaker fitted.

Previously, where there were alternate speaker vendors, this was
indicated using host CPU GPIOs.

Some new Dell models use spare pins on the CS35L63 as GPIOs for the
speaker ID detection.

Cirrus-specific SDCA Disco properties provide a list of the pins to be
used, and pull-up/down settings for the pads. This list is ordered,
MSbit to LSbit.

The code to set the firmware filename has been modified to check for
using chip pins for speaker ID. The entire block of code to set
firmware name has been moved out of cs35l56_component_probe() into
its own function to make it easier to KUnit test.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20260205164838.1611295-2-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>