Vikings rookie Will Reichard celebrated his first NFL game winner Saturday as he knocked through a 38-yard field goal as time expired to beat the Raiders. And in doing so, he got a cool nickname — Walk-off Will. Reichard’s first attempt of the day was no good. But we’ll remember the game winner. The Vikings were down 23-21. They got the ball back for one more series, as third-team quarterback Jaren Hall ran the offense. Then Reichard calmly walked out and made the kick to the delight of the fans at U.S. Bank Stadium in Minneapolis. Reichard was a star at Alabama. The Vikings selected him in th…