CANADA STOCKS-TSX falls as Rona bid dropped; Fed euphoria fades

* TSX down 40.98 points, or 0.33 percent, at 12,457.90 * Rona down more than 10 pct as Lowe's walks away from bid * Energy stocks limit losses as crude steadies By Alastair Sharp TORONTO, Sept 17 (Reuters) - Canada's main stock index fell on Monday, hurt by a drop in home improvement retailer Rona Inc after a potential suitor walked away and fading investor euphoria over last week's aggressive move by the U.S. Federal Reserve to spur growth. Rona fell more than 10 percent t