IMS: Abandon audio focus if no other call exist.

Sometimes call get disconnected due RTP inactive
when user dials empty URI list. Here telephony set
audio mode normal when foreground call get transit
to conf call. This triggers audio to initiate end
all calls.
Add code to check if there is any more call exist
before abandon audio focus.

Change-Id: I518053cb3f3ed8ab877e875e25460c14275891b8
CRs-Fixed: 935317
1 file changed