libcamera: Use const reference for range loops

Use a const reference in range-based for loops to avoid copies of the
loop elements.

While at it, change looping over controls in
PipelineHandlerUVC::processControls to use structured bindings.

Signed-off-by: Christian Rauch <Rauch.Christian@gmx.de>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/camera_manager.cpp

@@ -189,7 +189,7 @@ void CameraManager::Private::addCamera(std::shared_ptr<Camera> camera,
 {
 	MutexLocker locker(mutex_);
 
-	for (std::shared_ptr<Camera> c : cameras_) {
+	for (const std::shared_ptr<Camera> &c : cameras_) {
 		if (c->id() == camera->id()) {
 			LOG(Camera, Fatal)
 				<< "Trying to register a camera with a duplicated ID '"