In small bowl, toss 1/2 cup chocolate chips with 1 tablespoon of the dry cake mix. In large bowl, mix bananas, sour cream and eggs; beat with electric mixer on medium speed until well blended. Add remaining cake mix, water and oil; beat on low speed until combined. Beat 2 minutes on medium speed. Stir in coated chocolate chips; spoon into pan. Sprinkle with streusel.