Fix -Wunused-variable compiler warning

Test: presubmit
Change-Id: I146d3435fe76da7f300452a14b62ce430c38ae36
diff --git a/audio/aidl/default/Stream.cpp b/audio/aidl/default/Stream.cpp
index e8c1693..a805b87 100644
--- a/audio/aidl/default/Stream.cpp
+++ b/audio/aidl/default/Stream.cpp
@@ -582,7 +582,7 @@
     const size_t frameSize = mContext->getFrameSize();
     bool fatal = false;
     int32_t latency = mContext->getNominalLatencyMs();
-    if (bool success = readByteCount > 0 ? dataMQ->read(&mDataBuffer[0], readByteCount) : true) {
+    if (readByteCount > 0 ? dataMQ->read(&mDataBuffer[0], readByteCount) : true) {
         const bool isConnected = mIsConnected;
         LOG(VERBOSE) << __func__ << ": reading of " << readByteCount << " bytes from data MQ"
                      << " succeeded; connected? " << isConnected;