HONG KONG, Nov 2 (Reuters) – Chinese tech giant Tencent Holdings (0700.HK) and state-owned telecommunications firm China Unicom (600050.SS) have received regulatory approval to set up a so-called "mixed ownership" company, a public document showed on Wednesday. China has been accelerating its push for mixed-ownership reforms in an effort to boost the competitiveness of state firms. It was not immediately clear what the planned company would do. Shares in China Unicom surged 10% in Shanghai, forcing a temporary suspension of trade. Trade in its Hong Kong-listed shares (0762.HK) had ended before the news emerged as the stock market there was…