Updates prices, adds sector details March 17 (Reuters) - Canada's main stock index fell on Wednesday ahead of the U.S. Federal Reserve's policy decision, while data showed domestic inflation numbers edged higher in February. * Domestic inflation edged higher in February on rising gasoline prices, though the slight acceleration was below analyst expectations, data showed. * IT services provider Lightspeed POS Inc fell 3.3%, the most on the TSX, while the second biggest decliner was renewable energy firm Boralex Inc , down 2.4%.