kselftest/alsa: pcm - Support optional description for tests

In order to help with the comprehensibility of tests it is useful for us to
document what the test is attempting to cover. We could just do this through
comments in the configuration files but in order to aid people looking at
the output of the program in logs let's provide support for an optional
'description' directive which we log prior to running each of the tests.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221208-alsa-pcm-test-hacks-v4-5-5a152e65b1e1@kernel.org


Signed-off-by: Takashi Iwai <tiwai@suse.de>