LOS ANGELES (Reuters) – Rocker Steven Tyler on Thursday bowed out of his job as a judge on top-rated television singing contest "American Idol" for the coming season, saying he wants to dedicate himself to his band, Aerosmith. Tyler's departure comes as his fellow judge, Jennifer Lopez, also weighs whether to return to the program that once reigned supreme atop U.S. TV ratings but has seen its audience shrink in recent years. Third panelist Randy Jackson seems a likely bet to return this fall for the program's 12th season as either a judge or in a mentoring role. …