WASHINGTON (Reuters) -The U.S. Justice Department has sued to block a $4.3-billion proposed deal by Assa Abloy AB to buy a division of Spectrum Brands Holdings Inc that makes residential door hardware, the department said in a statement on Thursday which said the deal could lead to higher prices for consumers. The department said that a merger of Assa Abloy and Spectrum’s Hardware and Home Improvement division could mean higher prices and reduced innovation for homeowners who want to buy premium mechanical door hardware or smart locks. Sweden’s Assa Abloy makes Yale, August and EMTEK brands, w…