fix [3389263] OMX.Nvidia.h264.decode fails to shutdown

We were still destroying an ANativeWindow's buffer pretty soon
after it was removed from the window manager. This time
we really wait for the ISurace to go away.

Change-Id: I329273fedaeef76ee92836f6180c2c3808389330

services/surfaceflinger/Layer.cpp

@@ -150,8 +150,7 @@ status_t Layer::ditch()
     // the layer is not on screen anymore. free as much resources as possible
     mFreezeLock.clear();
 
-    EGLDisplay dpy(mFlinger->graphicPlane(0).getEGLDisplay());
-    mBufferManager.destroy(dpy);
+    // Free our own reference to ISurface
     mSurface.clear();
 
     Mutex::Autolock _l(mLock);