Camera2: fix a camera status bug

After a picture is taken for MMS app, the preview has been stopped in
onPictureTaken() but the camera state is subsequently set to IDLE in
ZSL mode. Add a check before assignment.

Change-Id: I0610a58dbccffdba4b94140d74942c2ff60c7882
CRs-Fixed: 675176
1 file changed