Fix 4g conference call logs are merged together

If the first participant is same with other call logs, these call
logs are treated as group so that shows one call log. In order to avoid
it, compare number separately. Otherwise, avoid to query contact with
post dial string that casues showing contact name for post dial string
if user stores it as contact.

Change-Id: Ifaea5c5c3ed70e5654fcb3ff6372681ae14896ac
CRs-Fixed: 1089412