Singer-actor Tom Waits filed a $2-million suit in federal court Tuesday against Frito-Lay, claiming the snack company used a sound-alike to promote one of its new products. Waits, whose growly delivery and street-smart vulnerability have earned him a cult following, claims in the suit, filed in Los Angeles, that Frito-Lay's 30-second radio advertisements for "Salsa Rio" Doritos infringe on his right to license the use of his voice. Waits' suit names Frito-Lay, based in Plano, Tex., and its advertising agency, Tracy Locke, based in Dallas. Waits seeks punitive damages of $2 million, plus unspecified actual damages and whatever profits Frito-Lay derived from the ads. Singer-actress Bette Midler recently won a similar case against Ford Motor Co. and a New York ad agency.