fix a typo that prevented preserveRects() to work properly

this caused drawing artifacts during the screen rotation
animation of SurfaceView.

Change-Id: Idcc996b6ca2e346135dd2264959670c0b086d4cb
diff --git a/services/surfaceflinger/Transform.cpp b/services/surfaceflinger/Transform.cpp
index 24d5f9a..05b7527 100644
--- a/services/surfaceflinger/Transform.cpp
+++ b/services/surfaceflinger/Transform.cpp
@@ -308,7 +308,7 @@
 
 bool Transform::preserveRects() const
 {
-    return (type() & ROT_INVALID) ? false : true;
+    return (getOrientation() & ROT_INVALID) ? false : true;
 }
 
 void Transform::dump(const char* name) const