Apple’s VP of Mobile Advertising Andy Miller will soon leave the company to join a venture capital firm, according to a new report. Citing sources close to the situation, AllThingsD reports that Miller will become a general partner at Highland Capital, a Boston-based venture firm. Notably, it was Highland that back Quattro Wireless, the mobile advertising company co-founded by Miller in 2006 and acquired by Apple in early 2010. The report states…