MEXICO CITY, Jan 5 (Reuters) - "Business as usual" in Mexico can result in dire consequences in the United States, as media tycoon Ricardo Salinas found out the hard way when U.S. regulators filed fraud charges against him this week. Accusations by the Securities and Exchange Commission (SEC) that Salinas pocketed $109 million in a debt deal and then engaged in an "elaborate scheme" to cover it up shocked a country accustomed to a far more lax regulatory environment. Salinas denies the charges. But some analysts say the case could change the way business is done in Mexico, leading to...