FRISCO, Texas — All systems point toward Dallas Cowboys quarterback Dak Prescott starting on Sunday against the Minnesota Vikings. Nothing is final, as Prescott must pass a certain threshold in his rehab from a right calf strain, coach Mike McCarthy said. But the Cowboys (5-1) plan for him to be on the field as they return from the bye and attempt to extend their five-game winning streak against the Vikings (3-3). However, it won’t be business as usual on the offensive line with former starting right tackle La’el Collins set to return from a five-game suspension for violating the NFL’s suspens…