IMS:3-way Conf Success,but held call refer fails

Scenario is -
A calls B,A calls C,B-Hold, C-Active, Merge
Merge success but only C is added to conference
B is on Hold
UI should display both calls.i.e.Conf call & held call

Avoid conference call state over writing held call state
as this call wasn't merged.

Change-Id: I2be872c446deb5625c47d50dd01fe5a714d148fa
CRs-Fixed: 770753