SANTA CLARA, Calif. — Mac Freeman, the Broncos’ chief commercial officer, made a promise last season. “When you come back to Denver, I’m going to get an office for you,” he told Steve Atwater, the Broncos’ Ring of Fame safety. Of course Atwater nodded, smiled his usual wide grin that belies his career as one of the game’s most feared tacklers in the 1990s, and said sure. But he gave Freeman’s comments little thought until he and his family decided to move back to the place they called home for a decade when he starred on the Broncos’ secondary from 1989-98. “I called Mac up and said, ‘Mac, were you serious about that or just joking?’” Atwater recalled.