IMS: Fix empty URI list dial after add participant.

Consider add participant when phone is in use and
in such case don't allow add participant with empty
uri list.
If phone is idle then don't treat dial request as
add participant. Rather allow dial with empty URI
list using conf uri dialer.

Change-Id: Ibefd3289155ba23a17c234a061b0a5136fbdf718
CRs-Fixed: 903527
1 file changed