ASoC: stm32: sai: fix sai probe

pcm config must be set before snd_dmaengine_pcm_register() call.

Fixes: 0d6defc7

 ("ASoC: stm32: sai: manage rebind issue")

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Link: https://lore.kernel.org/r/20200417142122.10212-1-olivier.moysan@st.com
Signed-off-by: Mark Brown <broonie@kernel.org>