give the proper orientation to the h/w composer HAL

we were using the "orientation" value instead of the
real transform, which may contain arbitrary rotations for
instance, and in some case ended up with a final "orientation"
that looked valid, but wasn't.

this fixes a problem on devices with a h/w composer hal where
the rotation animation looked weird.

Change-Id: I4be8a2a1bde49c33456fcf5c8d87ab515c216763
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 64eaecc..19c7ddd 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -196,13 +196,12 @@
      * 1) buffer orientation/flip/mirror
      * 2) state transformation (window manager)
      * 3) layer orientation (screen orientation)
-     * mOrientation is already the composition of (2) and (3)
+     * mTransform is already the composition of (2) and (3)
      * (NOTE: the matrices are multiplied in reverse order)
      */
 
     const Transform bufferOrientation(mCurrentTransform);
-    const Transform layerOrientation(mOrientation);
-    const Transform tr(layerOrientation * bufferOrientation);
+    const Transform tr(mTransform * bufferOrientation);
 
     // this gives us only the "orientation" component of the transform
     const uint32_t finalTransform = tr.getOrientation();