Sept 10 - Fitch Ratings has affirmed its ratings for M.D.C. Holdings, Inc. (NYSE: MDC), including the company's Issuer Default rating (IDR) at 'BBB-'. The Rating Outlook is Stable. A complete list of rating actions follows this release. MDC's ratings are based on the company's execution of its business model in the current moderately recovering housing environment, cautious land policies and solid...