Audio: Synchronous message posting for ALSA trigger commands

Audio: Synchronous message posting for ALSA trigger commands

BZ: 34971

In SST driver, whenever ALSA trigger commands are received from alsa framework,
driver schedules work queue.  Inside work queue, IPC message to LPE will be
sent.There will few milli seconds (depends on kernel threads) delay between
acknowledging ALSA with trigger command and actual start of operation by LPE.
ALSA expects trigger commands to be handled immediately and hence it is called
atomically.

Modify audio driver to post trigger message synchronously when trigger command
is received.

Change-Id: Ibb638e355bc06fac1923141b868be947238196b2
Signed-off-by: Namarta Kohli <namartax.kohli@intel.com>
Reviewed-on: http://android.intel.com:8080/47948
Reviewed-by: Abdullah, Omair M <omair.m.abdullah@intel.com>
Reviewed-by: Koul, Vinod <vinod.koul@intel.com>
Reviewed-by: Gupta, ArvindX K <arvindx.k.gupta@intel.com>
Reviewed-by: Hibare, PramodX <pramodx.hibare@intel.com>
Tested-by: Hibare, PramodX <pramodx.hibare@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>