kselftest/alsa: Report failures to set the requested channels as skips

kselftest/alsa: Report failures to set the requested channels as skips

If constraint selection gives us a number of channels other than the one
that we asked for that isn't a failure, that is the device implementing
constraints and advertising that it can't support whatever we asked
for. Report such cases as a test skip rather than failure so we don't have
false positives.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221201170745.1111236-4-broonie@kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>