SystemUI: Fix BT icon duplicate issue

The default code will add new icon to the beginning of the icon list,
this will change the index of the existed icon which will make the
system think it to be new and thus resulting duplicate icon issue.

Change to add the new icon to the end of the list.

Change-Id: I7335f418b1e0fc037fffe01f534f4d888e5cced7
CRs-Fixed: 1046294