Fix bug in conference call SRVCC.

1. Compare the state of original connection before handover with
the newly reported post-handover connection's state in order
to map the two connections as a result of SRVCC based on state.

2. Disconnect the IMS conference participants after SRVCC as the
new participants come via GsmCallTracker.

Bug: 22850703
Change-Id: I313e12d53ff9c096c0d2300e01b8733a3abe2776
2 files changed