IMS-VT: Handle full screen mode properly after ending VT call

- isFullScreen flag is not reset to false for race condition and
  next VT call can't update buttons properly at DIALING/ALERTING
  stage due to both shouldShowFullscreen and shouldShowGreenScreen
  are true.

- Reset isFullScreen to false once attemptCleanup in InCallPresenter

Change-Id: I59638a57e6e50f3a888868c7ee177ebe3cb0f858
CRs-Fixed: 3115017
1 file changed