Fix: EEVEE-Next: Irradiance Grid baking

Regression caused by e2cef1c713

source/blender/draw/engines/eevee_next/shaders/eevee_surfel_list_build_comp.glsl

@@ -32,5 +32,5 @@ void main()
   surfel_buf[surfel_index].ray_distance = ray_distance;
   /* NOTE: We only need to init the `list_start_buf` to -1 for the whole list to be valid since
    * every surfel will load its `next` value from the list head. */
-  // surfel_buf[surfel_index].next = atomicExchange(list_start_buf[list_index], surfel_index);
+  surfel_buf[surfel_index].next = atomicExchange(list_start_buf[list_index], surfel_index);
 }