The Chiefs made themselves at home when they were in Las Vegas in February for the Super Bowl.They practiced at the Raiders’ facility and used their locker room at Allegiant Stadium. Marquez Valdes-Scantling planted a Chiefs flag in the field after Kansas City won its second consecutive championship and third in five years.It was a nightmare for all those who bleed silver and black, but worse for them is how at home the Chiefs have felt when they’ve played the Raiders in Las Vegas. Kansas City (6-0) hopes to improve on its 4-0 record against the Raiders (2-5) at Allegiant when the teams meet Sunday.Oddsmakers don’t anticipate that being a problem. BetMGM Sportsbook made the Chiefs 9 1/2-point favorites, though the Raiders were the last team to beat Kansas City, winning there 20-14 last Christmas Day.“They came in and got after us,” Chiefs coach Andy Reid said. “That’s their personality …