ASoC: cs4265: Add a S/PDIF enable switch

This patch adds a S/PDIF enable switch as a SOC_SINGLE.

Signed-off-by: Matt Flax <flatmax@flatmax.org>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>