Fix potential ClassCastException.

It is possible for some of the Connections returned by getAllConnections()
in the CS to NOT be TelephonyConnections.  This is the case when an
ImsConferenceCall has received Conference Event Package data, and there are
ConferenceParticipantConnections present.

Bug: 26350817
Change-Id: I45c2c97e2462719cf3b858db70a20c9f9056f449
1 file changed