ASoC: stm32: spdifrx: fix inconsistent lock state

ASoC: stm32: spdifrx: fix inconsistent lock state

In current spdifrx driver locks may be requested as follows:
- request lock on iec capture control, when starting synchronization.
- request lock in interrupt context, when spdifrx stop is called
from IRQ handler.

Take lock with IRQs disabled, to avoid the possible deadlock.

Lockdep report:
[   74.278059] ================================
[   74.282306] WARNING: inconsistent lock state
[   74.290120] --------------------------------
...
[   74.314373]        CPU0
[   74.314377]        ----
[   74.314381]   lock(&(&spdifrx->lock)->rlock);
[   74.314396]   <Interrupt>
[   74.314400]     lock(&(&spdifrx->lock)->rlock);

Fixes: 03e4d5d56fa5 ("ASoC: stm32: Add SPDIFRX support")

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Link: https://lore.kernel.org/r/20191204154333.7152-2-olivier.moysan@st.com
Signed-off-by: Mark Brown <broonie@kernel.org>