"TROUBLE IN MIND." Sound track. Island. "Songs performed by Marianne Faithfull" proclaims the cover of this LP in large type, without telling you how many songs. That's enough to get fans of the smoky-voiced chanteuse excited--then disappointed when they find out that Faithfull does only two numbers. She sounds terrific on the title-track version of the classic blues tune, but it's taken at an extremely slow tempo. The other Faithfull number is a somber, mediocre Kris Kristofferson song called "The Hawk," and the remainder of the LP is filled out by Mark Isham's moody but not particularly memorable trenchcoat-under-a-lamppost, light-jazz score.