(Reuters) -Britain’s antitrust watchdog said on Wednesday it had started an investigation into Microsoft Corp’s $68.7 billion deal to buy “Call of Duty” maker Activision Blizzard Inc. The Competition and Markets Authority (CMA) said it had until Sept. 1 to make its phase 1 decision on whether the deal between the U.S. technology company and video-game maker Activision would reduce competition in the United Kingdom. “We’re committed to answering questions from regulators and ultimately believe a thorough review will help the deal close with broad confidence, and that it will be positive for com…