don't report an error when disconnecting from an abandoned surfacetexture

this happens often with CPU Surfaces, which disconnect long
after their surfacetexture has been abandoned.

Change-Id: If49da03b72f99130e01b2b9bcbd444bb38f7ed4e

Author: pixelflinger

libs/gui/SurfaceTexture.cpp

@@ -642,8 +642,9 @@ status_t SurfaceTexture::disconnect(int api) {
     Mutex::Autolock lock(mMutex);
 
     if (mAbandoned) {
-        ST_LOGE("disconnect: SurfaceTexture has been abandoned!");
-        return NO_INIT;
+        // it is not really an error to disconnect after the surface
+        // has been abandoned, it should just be a no-op.
+        return NO_ERROR;
     }
 
     int err = NO_ERROR;