libcamera: controls: Prevent copies of ControlId class

Now that the V4L2ControlId embedded in V4L2ControlInfo has been moved
out and doesn't require to be copied anymore, the base ControlId class
doesn't need to be copyable either. Delete the ControlId copy
constructor and copy assignment operator.

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

include/libcamera/controls.h

@@ -68,12 +68,11 @@ protected:
 		: id_(id), name_(name), type_(type)
 	{
 	}
-#ifndef __DOXYGEN__
-	ControlId &operator=(const ControlId &) = default;
-	ControlId(const ControlId &) = default;
-#endif
 
 private:
+	ControlId &operator=(const ControlId &) = delete;
+	ControlId(const ControlId &) = delete;
+
 	unsigned int id_;
 	std::string name_;
 	ControlType type_;