Blender Git Loki

Fix unnecessary Cycles OptiX kernel loading

With the OptiX viewport denoiser active, an OptiX device was added to the device list even when
rendering and denoising on different devices (e.g. CPU or CUDA) in background rendering. This
fixes it, so the OptiX device is only added when actually needed, as in only when OptiX denoising is
actually active in background rendering.