Apple Inc. and five bidding partners agreed to buy Nortel Networks Corp.’s remaining patents for $4.5 billion, giving them access to a portfolio of technologies used in mobile phones and tablet computers.   The bidding group included Microsoft Corp., Sony Corp, Research In Motion Ltd., Ericsson AB and EMC Corp., Ontario-based Nortel said in a statement. The bid trumped the $900 million Google Inc. had offered before the auction for Nortel’s remaining intellectual property.