Bob Dylan — the voice of his generation now known as an American “living national treasure,” and who is currently on tour — once called this landmarked Harlem townhouse his home. Now, the historic Renaissance Revival property can be yours for $2.75 million — a quarter of a million dollars less than its $3 million ask six months ago. The 19-foot-wide, four- to five-bedroom spread was designed by legendary Gilded Age architect Stanford White. Built in 1893, the home, at 265 W. 139th St., is