LOS ANGELES (Reuters) - One of Justin Bieber's hit songs is the target of a $10 million copyright infringement lawsuit that also accuses Bieber's mentor, R&B singer Usher, of funneling the song to the teen pop star. R&B singer Devin Copeland, known professionally as De Rico, and songwriter Mareio Overton filed a lawsuit last week in U.S. District Court in Virginia alleging that they came up with the song "Somebody to Love." Bieber, who is managed by one of Usher's business ventures, released "Somebody to Love" in 2010 with Usher also singing on the recording. The song peaked at No. 15 on the ...