IMS-VT: Remove one directional video call support

Remove one directional video call support thereby not giving
user the flexibility
1. to accept incoming video call as one way video call
2. to modify the call as one way video call
3. to accept incoming upgrade request as one way video call

Change-Id: I0c242d40a3d254b150ebeef354761fa67b17296f
CRs-Fixed: 1002286