In the case that someone calls CameraManager::start() and it has already started/enumerated, instead of returning -ENODEV, return -EBUSY. Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>