ASoC: soc-card: Add KUnit test case for snd_soc_card_get_kcontrol

Add a new snd-soc-card KUnit test with a simple test case for
snd_soc_card_get_kcontrol() and snd_soc_card_get_kcontrol_locked().

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://msgid.link/r/20240401100210.61277-4-rf@opensource.cirrus.com


Signed-off-by: Mark Brown <broonie@kernel.org>