ASoC: dapm: Only lock CODEC for I/O if not using regmap

If we do use regmap then regmap will take care of things for us. We
actually already have this check at a higher level for the current
users but this makes sure we do the right thing in the future too if
we need to.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>