nixos/x11: default to the modesetting driver

The upstream drivers are very dead:
- nouveau:
   - https://gitlab.freedesktop.org/xorg/driver/xf86-video-nouveau/-/commits/master
   - last meaningful change in August 2020
- ati (aka radeon):
   - https://gitlab.freedesktop.org/xorg/driver/xf86-video-ati/-/commits/master
   - last meaningful change in April 2020
- amdgpu:
   - https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/-/commits/master
   - barely alive, mostly thanks to Valve people

Modesetting isn't even the future, it's the now, especially with Wayland.
We should embrace it.

nixos/doc/manual/release-notes/rl-2305.section.md

@@ -134,6 +134,8 @@ In addition to numerous new and upgraded packages, this release has the followin
   [upstream's release notes](https://github.com/iputils/iputils/releases/tag/20221126)
   for more details and available replacements.
 
+- [services.xserver.videoDrivers](options.html#opt-services.xserver.videoDrivers) now defaults to the `modesetting` driver over device-specific ones. The `radeon`, `amdgpu` and `nouveau` drivers are still available, but effectively unmaintained and not recommended for use.
+
 ## Other Notable Changes {#sec-release-23.05-notable-changes}
 
 <!-- To avoid merge conflicts, consider adding your item at an arbitrary place in the list instead. -->

nixos/modules/services/x11/xserver.nix

@@ -256,7 +256,7 @@ in
 
       videoDrivers = mkOption {
         type = types.listOf types.str;
-        default = [ "amdgpu" "radeon" "nouveau" "modesetting" "fbdev" ];
+        default = [ "modesetting" "fbdev" ];
         example = [
           "nvidia" "nvidiaLegacy390" "nvidiaLegacy340" "nvidiaLegacy304"
           "amdgpu-pro"