ASoC: soc-cache: Apply the cache_bypass option

Incorporate the use of the cache_bypass functionality in the
syncing functions.  The snd_soc_flat_cache_sync() need not be
hooked as there is no performance benefit from using the
cache_bypass option.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>