Preheat oven o 375 F. Line 12 medium muffin cups with paper liners or spray bottoms with cooking spray. In a food processor, process oatmeal until it resembles coarse flour, about 15 seconds. Add flours, sugar, baking powder, baking soda, and salt. Pulse a few times to combine. Transfer mixture to a large mixing bowl. In processor, pulse bananas until coarsely mashed. Add soy yogurt and oil. Process until smooth. Add wet ingredients to dry ingredients and stir by hand, quickly and lightly, until just mixed. Batter will be thick. Divide batter evenly between prepared muffin cups. Sprinkle with coconut, if desired. Bake for 20-25 minutes.