Added stub for cecd:u service...

I couldn't find any information about this service...

src/core/hle/service/cecd_u.h

@@ -0,0 +1,27 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/hle/service/service.h"
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Namespace CECD_U
+
+namespace CECD_U {
+
+class Interface : public Service::Interface {
+public:
+    Interface();
+
+    /**
+     * Gets the string port name used by CTROS for the service
+     * @return Port name of service
+     */
+    std::string GetPortName() const override {
+        return "cecd:u";
+    }
+};
+
+} // namespace