ASoC: cs35l56: More KUnit tests for speaker ID

Merge series from Richard Fitzgerald <rf@opensource.cirrus.com>:

The first 3 patches in this series add some more KUnit testing for
fetching speaker ID and combining it with the system name to create
part of the qualifier for a firmware filename.

Patch #4 enables GPIOLIB in KUnit 'alltests' builds. This can be taken
separately from the first 3 patches.

The GPIO tests will skip if GPIOLIB is not enabled, but obviously it
would be ideal for 'kunit.py --alltests' runs to include these new
test cases.

diff --cc sound/soc/codecs/cs35l56-test.c
Simple merge