ASoC: Intel: use lock when changing SST state.

SST state change should be done under sst_lock

Signed-off-by: Mythri P K <mythri.p.k@intel.com>
Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>