CANADA STOCKS-TSX higher, lifted by CN Rail; banks weigh

(Adds portfolio manager comment, details; updates prices) By Alastair Sharp TORONTO, April 23 (Reuters) - Canada's main stock index edged narrowly higher in early trade on Wednesday, with better-than-expected profits at Canadian National Railway Co offset by dips in heavyweight bank shares. CN's results, reported after the markets closed on Tuesday, added to a cheery outlook from its chief rival, Canadian Pacific Railway Ltd, earlier that day. "All the rail companies are doing