nvidia_legacy_340: update to make it compatible with current kernel

[florianjacob]

Motivation for this change

The nvidia_legacy_340 version currently in NixOS is incompatible with pkgs.linuxPackages_latest, see #50707 for details.
This update to 340.107 fixes the compilation of the kernel module.

Fixes #50707.

As this is broken on 18.09 stable as well and the legacy versions only get bugfixes, I'd argue that backporting makes sense.

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.

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