By Jennifer Piacenti With Matthew Stafford battling an elbow injury, the Bills are now small road favorites for the season-opening game at the Rams. Odds are shifting in Las Vegas for the Rams-Bills season-opening game Sept. 8 at SOFI Stadium in Los Angeles. The Rams had opened as slight home favorites over the SI Sportsbook Super Bowl favorite Bills but now the Bills are slight road favorites. The home dogs have +110 odds, while the visiting Bills own -130 odds as of Wednesday. Matthew Stafford’s lingering elbow injury is likely the cause for the shift. Stafford has described the injury as “i…