aaudio: fix small underflow when a stream is stopped

Also remove inconsequential volume parameter.

Bug: 67910437
Test: test_aaudio_monkey.cpp and write_sine_callback.cpp
Change-Id: I6d11f3bfced3d579440f99c02d01a7d68af5c1e0
diff --git a/services/oboeservice/AAudioServiceStreamBase.cpp b/services/oboeservice/AAudioServiceStreamBase.cpp
index e670129..6246e7e 100644
--- a/services/oboeservice/AAudioServiceStreamBase.cpp
+++ b/services/oboeservice/AAudioServiceStreamBase.cpp
@@ -231,6 +231,8 @@
         return AAUDIO_ERROR_INVALID_STATE;
     }
 
+    setState(AAUDIO_STREAM_STATE_STOPPING);
+
     sendCurrentTimestamp(); // warning - this calls a virtual function
     result = stopTimestampThread();
     if (result != AAUDIO_OK) {