The President of the NAACP, Kweisi Mfume, calls the fall's major-network lineup a ''virtual whitewash,'' highlighting the blatant absence of black, Latino, or Asian actors in prominent roles in the new shows premiering on ABC, CBS, NBC, and Fox. Mfume called this ''a glaring omission,'' adding that ''African-Americans make up 13 percent of the population; we feel that our presence should be appropriately reflected.'' However, well-known producer, Steven Bochco, is creating a new show with a predominately Black cast.  By A. Long