lm: Move LM's class declaration into the cpp file

This isn't used directly outside of this translation unit, so we can
hide it from external use.

src/core/hle/service/lm/lm.h

@@ -4,21 +4,12 @@
 
 #pragma once
 
-#include <vector>
-#include "core/hle/kernel/kernel.h"
-#include "core/hle/service/service.h"
+namespace Service::SM {
+class ServiceManager;
+}
 
 namespace Service::LM {
 
-class LM final : public ServiceFramework<LM> {
-public:
-    LM();
-    ~LM() = default;
-
-private:
-    void OpenLogger(Kernel::HLERequestContext& ctx);
-};
-
 /// Registers all LM services with the specified service manager.
 void InstallInterfaces(SM::ServiceManager& service_manager);