ASoC: stm32: sai: Add missing cleanup

ASoC: stm32: sai: Add missing cleanup

The commit 0d6defc7e0e4 ("ASoC: stm32: sai: manage rebind issue")
converts some function calls to their non-devm equivalents.  The
appropriate cleanup code was added to the remove function, but not
to the probe function.  Add a call to snd_dmaengine_pcm_unregister
to compensate for the call to snd_dmaengine_pcm_register in case
of subsequent failure.

Fixes: commit 0d6defc7e0e4 ("ASoC: stm32: sai: manage rebind issue")
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Acked-by: Olivier Moysan <olivier.moysan@st.com>
Link: https://lore.kernel.org/r/1586099028-5104-1-git-send-email-Julia.Lawall@inria.fr
Signed-off-by: Mark Brown <broonie@kernel.org>