The prospect of legislative changes in the way the GSEs can do business has apparently spurred some lenders to adjust their plans for the future. According to a recent conference call, officials with Flagstar Bancorp are revising their long-term strategies in case Congress succeeds with legislation geared to rein in Fannie Mae and Freddie Mac. Flagstar, a Michigan-based lender that does a lot of business with Fannie, has decided to set up a new mortgage