Can't display atmosphere volume in solaris viewport

**Describe the bug**

Nothing is visible in the Solaris viewport when rendering with an Arnold Render Settings node that contains an Atmosphere Volume shader.

**To Reproduce**
Steps to reproduce the behavior:
1. plug atmosphere volume shader in the 'environnement' section of the arnold render settings
2. try to launch render in the solaris viewport
3. Nothing is visible

**Expected behavior**
Normally, the light should scatter through the fog.

**Used Software Versions**
- Arnold: [6.3.7.0]
- Houdini 20.5.487
- OS: [windows 10]


Reproduce the issue in the Solaris viewport with Arnold 6.3.7.0, Houdini 20.5.487, and the Arnold Render Settings node's Atmosphere Volume shader connected to the environment section. Compare viewport rendering with the expected light scattering through fog; done means the atmosphere volume is visible in the Solaris viewport.

Written by the indexing model from the issue text.