Some retailers have been offering credits or trade-ins for returns of HD-DVD players, but you always need to buy a new Blu-ray player in exchange. Circuit City is going them one better, extending its 30-day return policy to 90 days for HD-DVD players.Circuit City Stores Inc. is getting on the Blu-ray digital video format bandwagon by tripling the period in which customers who purchased a rival HD DVD player can return them.The nation’s No. 2 electronics retailer has instructed its stores to “take care of our