libmix: optimize the logic of checking available buffer

BZ: 105774

The old logic will call querySurfaceRenderStatus for every
allocated buffers on output port which is very time-consuming.

Change-Id: I5ce86e2db888720a457bf08ecd64fb0a492a4a37
Signed-off-by: Dan Liang <dan.liang@intel.com>
Reviewed-on: http://android.intel.com:8080/106697
Reviewed-by: Shi, PingX <pingx.shi@intel.com>
Reviewed-by: cactus <cactus@intel.com>
Tested-by: Shi, PingX <pingx.shi@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>
1 file changed