Federal regulators have completed the sale of troubled Superior Bank. But the thrift’s subprime unit is still on the block. In a deal announced last week, Cleveland-based Charter One Bank agreed to pay the Federal Deposit Insurance Corp. $52.4 million for 17 Superior branches and the rights to $1.1 billion in deposits. Charter One will also get close to $45 million in assets, including home-equity lines of credit and overdrafts assigned to each branch location.