IMS: Fix two addParticipant requests send to RIL

Do not treat addParticipant as emergency call case,
rather consider it as non-emergency call and broadcast
the Intent.
Clean up unnecessary codes and let to call addParticipant()
from TeleService after create connection.

Change-Id: I1c57c7e66155d43ac5ffb614abe054ab8df96b55
CRs-Fixed: 720697