Light function does not work with volumetric fog when not compatible with light atlas

Light functions do not work as intended with volumetric fog when using clamped mask textures which are not compatible with the light function atlas.

In light functions materials, when using any UV modifications (panner, texture coordinate, etc.) with "Compatible with Light Function Atlas" off, the opacity texture does not affect the volumetric shadows. When the texture mask relies on light function scale and UV Manipulation, the light function atlas cannot be used for those light functions.

1. Open a blank scene
2. Add a spot light pointing down to the floor. Set its Location's Z-coordinate to 400 and set its intensity to 10000.0 cd (this to make it easier to see the issue)
3. Set the intensity of the DirectionalLight to 0.0
4. Enable "Volumetric Fog" on the ExponentialHeightFog
5. Create a new material and open it
6. Set the Material Domain to Light Function
7. Plug a texture sample node into the material's Emissive Color input pin and set the texture to T_Dust_Particle_D
8. Plug a TexCoord node into the Texture Sample UVs input pin
9. Apply and save the material
10. In the editor console, set "r.LightFunctionAtlas 1"
11. The issue is that the volumetric fog cone will be solid instead of respecting the light function.
12. Verify that the light function does work by checking "Compatible With Light Function Atlas" on the light function material.