ALSA: hda: cirrus_scodec: fix an error code

The "ret" variable is zero but we should return -EINVAL.

Fixes: 2144833e7b41 ("ALSA: hda: cirrus_scodec: Add KUnit test")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/5eea7fd5-67c8-4ed4-b5b3-b85dfb7572cc@moroto.mountain
Signed-off-by: Takashi Iwai <tiwai@suse.de>

ALSA: hda: cirrus_scodec: Add KUnit test

Add a KUnit test for cirrus_scodec_get_speaker_id(). It is impractical
to have enough hardware with every possible permutation of speaker id.
So use a test harness to test all theoretically supported options.

The test harness consists of:
- a mock GPIO controller.
- a mock struct device to represent the scodec driver
- software nodes to provide the fwnode info that would normally come
from ACPI.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230918095129.440-3-rf@opensource.cirrus.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>