audiohal: Re-implement stream read and write using FMQ

Result: no hwbinder calls due read / write session.

Added IStream.close method for explicitly freeing up of resources
consumed by the stream before automatic server objects reaping
gets to it.

Test: make, perform Loopback RTT, check traces
Bug: 30222631
Change-Id: I678559f6ef30026685df787cd2ba7c2ee449ed27
diff --git a/audio/2.0/IStream.hal b/audio/2.0/IStream.hal
index 5c88a69..8de7851 100644
--- a/audio/2.0/IStream.hal
+++ b/audio/2.0/IStream.hal
@@ -279,4 +279,16 @@
      */
     getMmapPosition()
             generates (Result retval, MmapPosition position);
+
+    /*
+     * Called by the framework to deinitialize the stream and free up
+     * all the currently allocated resources. It is recommended to close
+     * the stream on the client side as soon as it is becomes unused.
+     *
+     * @return retval OK in case the success.
+     *                NOT_SUPPORTED if called on IStream instead of input or
+     *                              output stream interface.
+     *                INVALID_STATE if the stream was already closed.
+     */
+    close() generates (Result retval);
 };