A South End rapper awaiting trial on charges he tried to bilk The One Fund Boston for victims of the marathon bombing out of nearly $2.2 million has hit back with a federal lawsuit, accusing state police of setting him up “through police misconduct.” Branden “The Real SouljaBoy” Mattier, who is serving as his own counsel on the civil matter, is seeking $100,000 in damages. The case, filed Dec. 23 in U.S. District Court in Boston, has been assigned to Magistrate Judge Marianne B. Bowler. Mattier states in court filings he has “never worked.”