China’s widening curbs on iPhone use by government staff intensified a sell-off in global tech stocks on Friday on fears Apple and its suppliers could take a hit from rising Sino-U.S. tensions and growing competition from Huawei. Apple shares (AAPL-Q) have tumbled 6.4% over the last two days, wiping $190 billion from its market capitalization, following news Beijing ordered some central government employees in recent weeks to stop using iPhones at work. Several Wall Street analysts on Friday said the selloff was overdone, saying any revenue hit for Apple would likely be small due to the phone’s popularity in China....