SUMMER TIME When it was released, "Love to Love You Baby" was pretty risque, what with all that "oohing" and "aahing." Of course, by today's standards, the 1975 hit that transformed Donna Summer into a hypersexual disco diva is pretty tame. "Innocent even," she said yesterday from Los Angeles. "There's much worse out there now." Summer, who lived in Brookline and Newton as a girl, sometimes singing at the Grant African Methodist Episcopal Church on Washington Street, is making a comeback of sorts. She's got a new best-of CD and a book, titled "Ordinary Girl: The Journey," which recounts her rise to superstardom, and the bumps and bruises along the way (Summer, who's happily married and has three kids, had her share of abusive boyfriends). "In order to write about certain things, I had to pull them out and, painfully, experience them all over again," she said. "At one point, I called the publisher and said, `I can't do this.' " As for "Love to Love You Baby," which Summer has refused to perform for more than 20 years, she doesn't regret the song, just what it did to her image. "It wouldn't have been my choice for a first record, but that's not the way my life went," she sighed. "Many a baby was birthed to that one. . . . Know what I mean?"