Update with Sent message on UI on receiving last ack of MO long SMS

Issue: Sent message is get updated on UI for each ack of SMS part in
long SMS.It should be shown only for successful sent of last SMS part
of long message.
Fix: Updated Sent message on UI for successful sent of last SMS part
of long message.

Change-Id: Ic6add58b64770ef2eca2fc9cb3efd1571e42c5ba
CRs-Fixed: 719962