By Tzvi Machlin Heading into the final year of his rookie contract, New York Giants running back Saquon Barkley needs to have a big year in order to get a big extension next offseason. To that end, he’s willing to play an even bigger role in the offense this year. Per SNY’s Ralph Vacchiano, Barkley has been lining up at wide receiver on top of his usual RB duties. Barkley told the media that it’s part of an effort by the team to open up the offense more. Though he admitted that he hasn’t done that sort of work since college. “I think it’s helpful, not only for myself, but opening up other thin…