IMS-VT : Set the flag to start call with speaker on for incoming VT calls

- There seems to be a race condition between when InCallUI
  enters the video mode and sets the speaker phone on and
  when call state changes to active.

- As a result, the audio route gets reset to earpiece as we
  are not setting speaker phone on flag for the incoming
  case. This change fixes that issue

Change-Id: I3e665cbd426da0f321d85cd4a23310776c80cc96
CRs-Fixed: 741320