remove unneeded fully qualified name

Signed-off-by: tobiaskaminsky <tobias@kaminsky.me>

src/main/java/com/owncloud/android/ui/activity/ReceiveExternalFilesActivity.java

@@ -833,7 +833,7 @@ public class ReceiveExternalFilesActivity extends FileActivity
     }
 
     private Vector<OCFile> sortFileList(Vector<OCFile> files) {
-        FileSortOrder sortOrder = PreferenceManager.getSortOrder(this, mFile);
+        FileSortOrder sortOrder = getSortOrder(this, mFile);
         return sortOrder.sortCloudFiles(files);
     }