fix setting/unsetting hover on thumbnailed screens

cleaned up dragenter / dragexit events so they're only received by CellLayouts if the workspace isn't small

ignoring enter/exit scrollarea events when workspace is small

src/com/android/launcher2/CellLayout.java

@@ -1088,8 +1088,6 @@ public class CellLayout extends ViewGroup implements Dimmable {
             mDragCell[0] = -1;
             mDragCell[1] = -1;
 
-            setHover(false);
-
             // Fade out the drag indicators
             if (mCrosshairsAnimator != null) {
                 mCrosshairsAnimator.animateOut();