LOS ANGELES (Reuters) - Madonna retained the title Queen of Pop by taking the throne of the Billboard 200 album chart for the eighth time on Tuesday, as her latest album "MDNA" beat Lionel Richie's country themed "Tuskegee" to the top of the weekly sales list. Madonna's 12th studio album, dedicated to club-friendly dance tracks, sold 359,000 copies in its first week according to Nielsen SoundScan, despite lukewarm reviews from critics and minimal promotional appearances by the singer. This is the fifth time in the 53-year-old singer's career that her album has debuted at No. ...