SHANGHAI, May 18 (Reuters) - Hong Kong stocks ended roughly flat on Wednesday as a recent recovery ran out of steam, with some investors worried that Beijing's stimulus may not be adequate to revive the coronavirus-battered economy. ** Both the benchmark Hang Seng Index and the Hang Seng China Enterprise Index edged up 0.2%. ** Chinese Vice-Premier Liu He soothed tech sector's nerves on Tuesday, saying the...