IMS-VT: Reset zoom value in UI while switching camera.

When camera is switched, preview is restarted with default
zoom value. However the zoom value in ui was holding the previous
value causing mismatch between actual preview zoom and the zoom
controller bar position.

Change-Id: Iadec26e97afaef6ac47981ef42623a8822a4811f
CRs-Fixed: 2039539
1 file changed