SACRAMENTO, Calif. — The lawyer for Sirhan Sirhan, who assassinated presidential candidate Robert F. Kennedy in 1968, on Wednesday asked a judge to free him and played a recording of her client saying he is now dedicated to nonviolence and wants only to “return home to my brother and live the rest of our days in peace.”Sirhan, 78, has spent 54 years in prison. In the message played during a news conference held by his lawyer, he said he feels remorse every day for his actions.“To transform this …