BQ: fix Volantis test failures

The Volantis driver will dequeue a buffer in eglCreateWindowSurface.

- Remove the requirement that no buffers be dequeued when calling
  setAsyncMode() on a BufferQueueProducer, since this gets called
  from eglSwapInterval.
- Modify the tests to call setMaxDequeuedBufferCount before calling
  eglCreateWindowSurface.

Change-Id: Icc64e9933f151771bbd57035549cd5928c0b7216
diff --git a/include/gui/IGraphicBufferProducer.h b/include/gui/IGraphicBufferProducer.h
index be1874a..b8cba2f 100644
--- a/include/gui/IGraphicBufferProducer.h
+++ b/include/gui/IGraphicBufferProducer.h
@@ -113,14 +113,10 @@
     // allow for the asynchronous behavior. If it is not enabled queue/dequeue
     // calls may block.
     //
-    // This function should not be called when there are any currently dequeued
-    // buffer slots, doing so will result in a BAD_VALUE error.
-    //
     // Return of a value other than NO_ERROR means an error has occurred:
     // * NO_INIT - the buffer queue has been abandoned.
-    // * BAD_VALUE - one of the below conditions occurred:
-    //     * client has one or more buffers dequeued
-    //     * this call would cause the maxBufferCount value to be exceeded
+    // * BAD_VALUE - this call would cause the maxBufferCount value to be
+    //               exceeded
     virtual status_t setAsyncMode(bool async) = 0;
 
     // dequeueBuffer requests a new buffer slot for the client to use. Ownership