hardware/qcom/audio: Fix for Crash during Gtalk startup

 -Crash is observed when Hangouts and Gtalk start running
  simultaneously
 -Dirver does not support multiple instances of voip call.
 -Avoid creating multiple voip session if mVoipStreamCount
  is already 2
CRs-Fixed: 440160
(cherry picked from commit b9f1299e4ca8b96907f97914a0cf65fd5a3d3174)

Change-Id: I7ef3cf76394e1469db9d21a1484aacf1251c4f25