CANADA STOCKS-TSX little changed as investors await Yellen speech

* TSX dips 7.35 points, or 0.05 percent, to 15,554.60 * Seven of 10 main index sectors advance * Goldcorp, Barrick slip with bullion price By John Tilak TORONTO, Aug 21 (Reuters) - Canada's main stock index was little changed on Thursday as investors digested mixed economic data and awaited a speech from U.S. Federal Reserve Chair Janet Yellen for clues on the direction of the central bank's monetary policy. Figures showed a bigger-than-expected drop in the number of America