(Refiles to fix advisory, adds data in paragraphs 13-14) By Yantoultra Ngui and Kane Wu SINGAPORE/HONG KONG (Reuters) -U.S.-based investor Stonepeak is seeking to raise as much as $4 billion for its second Asia-focused infrastructure fund, a source with direct knowledge of the plan said, as investors seeking lucrative long-term returns drive a wave of new investments in the region. Stonepeak expects to reach $1 billion, or a quarter of its target, by the end of this month, four months after its launch ...