HONG KONG, May 25 (Reuters) - Chinese chip maker Changxin Memory Technologies Inc (CXMT) has appointed investment banks CICC (3908.HK) and China Securities (6066.HK) as sponsors for its planned domestic initial public offering (IPO), two people with knowledge of the matter said. CXMT, owned by state-backed parent Innotron Memory Co, is China's leading maker of DRAM memory chips. Bloomberg reported in April that CXMT's IPO would target a valuation of more than $14.5 billion. The sources said a handful of other local investment banks are expected to take more junior roles in the deal, and bookrunners for the offering had...