Motivation for this change

My network card defaults to the r8169 driver. That however has a bug where it sometimes stops working after a suspend. So I'm packaging the alternative, which works flawless.

@samueldr since just picking this package from the unstable channel isn't feasible (kernel versions have to match), would it be okay if I also add this to release-18.09?

Also this is my first kernel module so I'd appreciate it if someone reviews this.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Fits CONTRIBUTING.md.