By Neil Maidment LONDON (Reuters) – Britain’s biggest sporting goods retailer Sports Direct posted a 12 percent rise in quarterly sales, with growing demand at its sports stores tempered by a drop in its profitability and falling sales at its fashion and brands businesses. Mark-downs to clear stock in Austria following the acquisition of Eybl in May 2013, and in the UK, after England’s poor showing at the soccer World Cup in Brazil, helped take 10 basis points of the group’s gross margin in its first quarter. …