PRESIDENTIAL NAMESAKE: It may not be too many years before little John Kennedy DeVine of Granger Avenue will be old enough to travel to Cambridge, Mass., to see the John F. Kennedy Memorial Library on the banks of the Charles River. Meanwhile, his father, local attorney John B. DeVine, is busy in his post as Michigan chairman for the Kennedy library fund. Mrs. DeVine is a cousin of the late President. Her mother, Mrs. Charles J. Burke of Chestnut Hill, Mass., is a sister of Joseph P. Kennedy. Little John's sisters, Margot, Ann, Kathleen and Susan, are visiting Mrs. Burke now at her summer home in North Scituate, Mass. Contributions to the Kennedy Library may be mailed to the John F. Kennedy Library, Inc., at 260 Tremont St., Boston, Mass. 02116, or to P. O. Box 659, Detroit, Mich.