(Reuters) – Multiple Olympic and world champion Mo Farah said his elite track career could be over after he finished runner-up in the London 10,000 on Monday on his return to action. Farah, who completed the 5,000 and 10,000 metres double at the 2012 and 2016 Olympics, was racing for the first time since June after failing to qualify for last year’s Tokyo Games. The 39-year-old Briton finished a minute outside his best time at the London course in 2010 as he was out-sprinted by 26-year-old club runner Ellis Cross, who finished four seconds ahead with a time of 28:40. “In terms of the track, th…