Cal Performances sponsored a few events last month, but for many, the season opened at Zellerbach Hall Friday, Sept. 30, with the world premiere of “Layla and Majnun,” Mark Morris’ choreographed retelling of a classic Persian legend, set to exquisite Azerbaijani music by early 20th century composer Uzeyir Hajibeyli. Members of the remarkable Silk Road Ensemble and two great vocalists in the mugham style, Fargana Qasimova and Alim Qasimov, performed the arranged score, and they presented a problem by dividing our attention.