Fix preview state machine after it's restarted due to ratio changes

The camera state was being set to PREVIEW_STOPPED by the restart,
and the lack of a completion message was leaving it in that state,
breaking other checks down the line (changing scene/balance modes,
for instance, failed miserably)

Change-Id: Ia5bc6b1aab5ee85582c4c4c3d09646892e669454