Feb 15 (Reuters) – Charlie Munger, the longtime business partner of Warren Buffett at Berkshire Hathaway Inc (BRKa.N), on Wednesday said China remains a top opportunity for investors despite geopolitical risks. Munger also doubled down on his recent Wall Street Journal editorial calling for the U.S. government to follow China and ban cryptocurrency, saying "people who oppose my position are idiots." The 99-year-old spoke while fielding 2-1/4 hours of questions at the annual meeting of Daily Journal Corp (DJCO.O), a Los Angeles newspaper publisher and provider of software to courthouses that he chaired for 45 years and where he remains…