ASoC: sst_platform created helper functions

Few funtions can be modularized in this driver to make them look cleaner
like managing the stream status with locks and filling pcm parameters.

This patch adds helper functions to do the same.

Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Harsha Priya <priya.harsha@intel.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>