Fix to attach listener to transient session

There can be race condition between updating the final transient
session as primary session in ImsCall and processing of
UNSOL_REFRESH_CONF_INFO msg which can lead to incomplete update of
conference participants state to the UI.
To fix this copy the old listener in host ImsCallSession
to the newly created transient session.

Change-Id: Ia68ccc5c5a9d6970b18b556279ef7abd53f7b743
CRs-Fixed: 2782644
1 file changed