Fixing issue with cancelled drag blocking cell spaces (Issue 5386523)

Change-Id: I9cfc728edeeee2237c21935517107e7a2af49646

src/com/android/launcher2/DragController.java

@@ -361,6 +361,7 @@ public class DragController {
             if (mLastDropTarget != null) {
                 mLastDropTarget.onDragExit(mDragObject);
             }
+            mDragObject.cancelled = true;
             mDragObject.dragComplete = true;
             mDragObject.dragSource.onDropCompleted(null, mDragObject, false);
         }