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