Mortgage lenders are taking lots of legal fires. Borrowers claim they were deceived. Investors allege they were defauded. And regulators want to hold them accountable for foreclosure-process abuses. Massachusetts Attorney General Martha Coakley sued mortgage companies last week and one national lender promptly announced it would end most of its business in the state. Mortgage companies have plenty of problems, but Martha Coakley didn’t create them. Most were self-inflicted.