Apple has been asking its suppliers to study the possibility of moving iPhone production to the U.S., according to a new report by Nikkei Asian Review. Back in June, Apple reportedly approached both of its major iPhone assemblers, Foxconn and Pegatron, asking them to look into making iPhones in the U.S.; Foxconn agreed, but Pegatron declined due to cost concerns. Sources for the report indicated that although Foxconn has been working on outlining…