ASoC: adav80x: Update locking around use of DAPM pin API

The pin updates in this driver look like they are intended to be done
atomically, update to do so.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>