A resurgent housing market boosted earnings at some regional banks such as U.S. Bancorp (USB) and M&T Bank (MTB) in the third quarter, though low margins on those new loans plague banks overall. And regional bank Comerica (CMA) said a decline in higher-yield commercial mortgages crimped its Q3. Minneapolis-based U.S. Bancorp reported per-share earnings of 74 cents, up 16% from a year ago, but mere in line with analyst forecasts. Mortgage banking