(debtor's prohibited from confirming Chapter 11 reorganization plan containing cramdown provision that proposed to sell the debtor's property at auction clear of bank's lien where sale proceeds would be used to repay bank but where bank not permitted bank to credit-bid (using the debt owed the bank to offset purchase price) at auction; 11 U.S.C. Sec. 1129(b)(2)(A) does not allow debtors to sell encumbered assets free and clear of lien without allowing credit-bidding).