Audio primary hal: fix member function used before init

prepare for write was refactor by Ib4170eb6a9f88f9352d0912083b43d600771bb8e
to use temporary variable in a rai pattern.
Nevertheless the member variable was still used too early in
prepareForRead resulting in a crash for capture.

Test: assistant, camcorder
Bug: 37492059

Change-Id: I08140834959c440798cd40700dd089adca2f3e40
Signed-off-by: Kevin Rocard <krocard@google.com>
(cherry picked from commit 34b44cd7dba0ae9bd7c51fdb3677a7a28741fc1e)
diff --git a/audio/2.0/default/StreamIn.cpp b/audio/2.0/default/StreamIn.cpp
index 0798bbe..e5a1a55 100644
--- a/audio/2.0/default/StreamIn.cpp
+++ b/audio/2.0/default/StreamIn.cpp
@@ -354,7 +354,7 @@
                 CommandMQ::Descriptor(), DataMQ::Descriptor(), StatusMQ::Descriptor(), threadInfo);
         return Void();
     }
-    status = mReadThread->run("reader", PRIORITY_URGENT_AUDIO);
+    status = tempReadThread->run("reader", PRIORITY_URGENT_AUDIO);
     if (status != OK) {
         ALOGW("failed to start reader thread: %s", strerror(-status));
         _hidl_cb(Result::INVALID_ARGUMENTS,