For David Krumholtz, to slip back in time, he simply has to slip out of style. As 1970s porn director Harvey Wasserman on HBO’s The Deuce, “once I put on the polyester and the ’70s-era shoes that hurt my feet, I find my way into the character,” the actor, 40, tells Us. “The mustache helps, too.” Come season 2 (premieres Sunday, Sept. 9, at 9 P.M.), he’ll take on a new look — Krumholtz recently dropped more than 100 pounds! — and a new attitude. “I always imagine Harvey as someone who came from a good family with a brother that’s a doctor, a sister that’s a lawyer and somehow he ended up making porn and living with that shame,” the Good Wife alum admits. “But now, he revels in…