libcamera: camera_manager: Enforce unique camera IDs

The camera ID is documented that it should be unique but it's not
enforced. Change this by refusing to add cameras to the CameraManager
that would create two cameras with the exact same ID.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/camera_manager.cpp

@@ -182,10 +182,10 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
 
 	for (std::shared_ptr<Camera> c : cameras_) {
 		if (c->id() == camera->id()) {
-			LOG(Camera, Warning)
-				<< "Registering camera with duplicate ID '"
+			LOG(Camera, Fatal)
+				<< "Trying to register a camera with a duplicated ID '"
 				<< camera->id() << "'";
-			break;
+			return;
 		}
 	}