fix [2425395] portrait UI briefly shows in landscape

the "freeze" timeout was not initialized properly which caused it
to kick-in immediately instead of after 5s
diff --git a/libs/surfaceflinger/SurfaceFlinger.cpp b/libs/surfaceflinger/SurfaceFlinger.cpp
index 66ac4d2..2598440 100644
--- a/libs/surfaceflinger/SurfaceFlinger.cpp
+++ b/libs/surfaceflinger/SurfaceFlinger.cpp
@@ -625,12 +625,13 @@
 
             mVisibleRegionsDirty = true;
             mDirtyRegion.set(hw.bounds());
-            mFreezeDisplayTime = 0;
         }
 
         if (mCurrentState.freezeDisplay != mDrawingState.freezeDisplay) {
             // freezing or unfreezing the display -> trigger animation if needed
             mFreezeDisplay = mCurrentState.freezeDisplay;
+            if (mFreezeDisplay)
+                 mFreezeDisplayTime = 0;
         }
 
         if (currentLayers.size() > mDrawingState.layersSortedByZ.size()) {