'American Idol' Star Nikko Smith -- That's NOT My Penis ... In 'Love & Hip Hop' Sex Tape

Former "American Idol" finalist Nikko Smith wants the world to know ... he is NOT the Nikko Smith who stars in a sex tape with "Love & Hip Hop" star Mimi Faust -- but he's not exactly embarrassed by the mistaken identity.Nikko -- who placed 9th…