Camcorder: Switch video torch when preview focused

- Currently, video torch switching is not determined
  properly. When user enables and disables flash mode
  checkbox, nothing happens. Also, if video torch
  is enabled and switching to Camera and back to
  Camcorder mode, torch doesn't lights up.

- Adding a local variable mPreviewFocused to track
  the preview window focus state should fix the issue.

Change-Id: Ia134b86885eda1ad50d510e67e5595a391326d10
CRs-fixed: 567295
Camera: Don't do cancel_af till all CBs are received in burst shot

Doing cancel_af in the first jpeg CB while
burst shot is going on, is changing the
camera state to IDLE and allowing next
takePicture() which is resulting in crash
as this call reaches HAL when camera is in
picture taking state.

Change-Id: Idd146060a73161bcc30c34756fb53662bb1f0902
CRs-Fixed: 593352