WASHINGTON — The Federal Election Commission has dismissed a complaint against Sen. John Ensign over a $96,000 payment his parents made to his former mistress and her family.Citizens for Responsibility and Ethics in Washington, a campaign finance watchdog group, announced Friday that the commission had dismissed its complaint against Ensign, his parents, his campaign and his political action committee over the money paid to Cynthia Hampton, with whom the Nevada Republican has admitted having an affair.