libmix: code cleanup along with new API to support one Queue buffer management

BZ: 24552

code cleanup along with new API to support one Queue buffer management (from Andy)

Change-Id: I1424915b52da05e38a72f2c04adc88cdc988f14d
Reviewed-on: http://android.intel.com:8080/36031
Reviewed-by: Chen, Weian <weian.chen@intel.com>
Reviewed-by: Qiu, Junhai <junhai.qiu@intel.com>
Reviewed-by: Ding, Haitao <haitao.ding@intel.com>
Tested-by: Ding, Haitao <haitao.ding@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
3 files changed