ASoC: soc-cache: Add error checking in the *_cache_sync functions

Ensure that we report any errors encountered during reads/writes
in the cache syncing functions.

Remove redundant newline in the source code.

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>