audioflinger: fix ro.audio.silent in offload mode

Change-Id: I5a1a79000d53146689b0a198cc5419c36509703f
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 1b5a9a9..3578b7d 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -3509,7 +3509,8 @@
 
             if (track->mFillingUpStatus == Track::FS_FILLED) {
                 track->mFillingUpStatus = Track::FS_ACTIVE;
-                mLeftVolFloat = mRightVolFloat = 0;
+                // make sure processVolume_l() will apply new volume even if 0
+                mLeftVolFloat = mRightVolFloat = -1.0;
                 if (track->mState == TrackBase::RESUMING) {
                     track->mState = TrackBase::ACTIVE;
                 }
@@ -3887,7 +3888,8 @@
             ALOGVV("OffloadThread: track %d s=%08x [OK]", track->name(), cblk->mServer);
             if (track->mFillingUpStatus == Track::FS_FILLED) {
                 track->mFillingUpStatus = Track::FS_ACTIVE;
-                mLeftVolFloat = mRightVolFloat = 0;
+                // make sure processVolume_l() will apply new volume even if 0
+                mLeftVolFloat = mRightVolFloat = -1.0;
                 if (track->mState == TrackBase::RESUMING) {
                     if (mPausedBytesRemaining) {
                         // Need to continue write that was interrupted