SANTA CLARA, Calif. (AP) — The San Francisco 49ers are one win away from accomplishing a turnaround that’s been done only once before in the Super Bowl era. With a victory in the NFC championship game at home on Sunday against the Green Bay Packers, the Niners will become the second team in NFL history to make the Super Bowl a year after losing at least 12 games. Only the St. Louis Rams have…