If secondary market players thought they had put the predatory lending issue behind them, they got a chilling reminder this week when a leading investment bank revealed that it has been targeted in a government probe of business practices in the subprime market. The revelation came in a securitization prospectus filed Dec. 30 by Bear Stearns, which disclosed that its EMC Mortgage subsidiary, which acquires and services primarily non-conforming mortgages, had been contacted by