(Reuters) - A Wells Fargo banker, Chenyue Mao, who had been barred from leaving China for several months, has been allowed to return to the United States following negotiations between U.S. and Chinese officials, according to two people with knowledge of the case. Mao, who works in Wells Fargo's international factoring business, was prevented from leaving China due to her involvement in a criminal case, China's Foreign Ministry said in July. The ministry said Mao had been required to cooperate with an inv ...