Transform update spectrum event into message.

firmware/common/message.hpp

@@ -50,6 +50,7 @@ public:
 		Shutdown = 8,
 		AISPacket = 7,
 		ERTPacket = 9,
+		UpdateSpectrum = 10,
 		MAX
 	};
 
@@ -260,6 +261,14 @@ public:
 	baseband::Packet packet;
 };
 
+class UpdateSpectrumMessage : public Message {
+public:
+	constexpr UpdateSpectrumMessage(
+	) : Message { ID::UpdateSpectrum }
+	{
+	}
+};
+
 class MessageHandlerMap {
 public:
 	using MessageHandler = std::function<void(Message* const p)>;