BUG-429: Rework Termination Point state handling

It turns out that MD-SAL does transaction reordering and provides not
guarantees to data visibility between transactions. Until that is fixed,
do not rely on data in MD-SAL, but rather do our own state tracking.

Change-Id: Idf1a14f9f61c78d651e3f29970faa87436bdb8ca
Signed-off-by: Robert Varga <rovarga@cisco.com>