“The Butler” director Lee Daniels says Mariah Carey, who plays a slave in the upcoming flick, is “a diva — but in a great way.” He told us last week, “She’s a lady and fun. She doesn’t take her diva role seriously.” While the movie, starring Oprah Winfrey, Robin Williams and John Cusack, is getting early buzz, Daniels admitted he’s still reeling over searing reviews of “The Paperboy” with Nicole Kidman and Zac Efron. “They killed me, like, hey, what the . . . ” he said. “I worry about it for actors. They give everything to me and I believe all those actors were seen in a light they have never been seen in before.”