ASoC: apple: mca: Improve handling of unavailable DMA channels

[ Upstream commit fb1847cc ]

When we fail to obtain a DMA channel, don't return a blanket -EINVAL,
instead return the original error code if there's one. This makes
deferring work as it should. Also don't print an error message for
-EPROBE_DEFER.

Fixes: 4ec8179c

 ("ASoC: apple: mca: Postpone requesting of DMA channels")
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20230224153302.45365-3-povik+lin@cutebit.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>