Liberty Media Corp. said the closing of its acquisition from RMS L.P. of a controlling interest in Home Shopping Network Inc. has been delayed.Liberty Media said the transaction is subject to certain regulatory consents that have not yet been received. The company said the agreement to purchase the stock has been extended and it now expects the closing to take place early in 1993. Granite Broadcasting Corp. said it extended to Jan. 13 its exchange offer for $ 60 million principal amount of the company’s 12.75% senior subordinated debentures due Sept. 1, 2002. The company indicated that about $ 58.5 million of the bonds had been tendered to date. The offer had been set to expire today.