fix: resolve narrowing conversion issue in mm_u.cpp

- Added explicit cast to address narrowing conversion warning in the initializer list for `IPC::ResponseBuilder`.
- Ensured compatibility with strict type conversion requirements.

src/core/hle/service/mm/mm_u.cpp

@@ -78,7 +78,7 @@ private:
             request_id = rp.Pop<u32>();
         }
 
-        IPC::ResponseBuilder rb{ctx, extra_data ? 3 : 2};
+        IPC::ResponseBuilder rb{ctx, static_cast<u32>(extra_data ? 3 : 2)};
         rb.Push(result);
         if (extra_data != 0) {
             rb.Push(extra_data);