There is an updated pull request by MrLimb against master on the void-packages repository

https://github.com/MrLimb/void-packages master
https://github.com/void-linux/void-packages/pull/24591

nvidia390: adding a patch for linux5.8
Fixing the nvidia drivers, again. Hello, @ericonr . 

A patch file from https://github.com/void-linux/void-packages/pull/24591.patch is attached