IMS-VT: Dismiss zoom controller dialog after camera is closed.

-Zoom controller always there when switch VT call between forground
and backgound, zoom value with max is not correctly after back to
forground if video cannot be paused as camera is closed.

-Dismiss zoom controller dialog once call goes backgound.
-Reset zoom index to default value if video cannot be paused
after call goes backgound.

Change-Id: I4ebb37eb5fcb563f2edd5c3b63b51cd1c934ca20
CRs-Fixed: 2888546
1 file changed