By Eva Mathews (Reuters) -Nearly 2 billion pounds was wiped off JD Sports Fashion’s market value on Thursday, after the British sportswear giant warned on annual profit, citing tepid consumer spending that bruised peak season sales and led to heavy discounting. The retailer, which sells Nike, Adidas and other sports fashion ranges, said softer demand and more promotional activity than expected dented gross margins in the peak 22-week period ended Dec. 30. It now expects profit before tax of 915-935 million pounds ($1.16-1.19 billion) for the year ending Feb. 3, down from a previous forecast in…