Federal prosecutors Thursday asked a judge to give singer R. Kelly 25 more years in prison for his child pornography and enticement convictions last year in Chicago, which would add to 30 years he recently began serving in a New York case.The 56-year-old wouldn’t be eligible for release until he was around 100 if the judge agrees both to the 25-year sentence and another government request that Kelly begin serving his Chicago sentence only after the 30-year New York sentence is fully served.In their sentencing …