nixos/initrd-network: use ipconfig from klibc
nixos/initrd-network: use ipconfig from klibc

This apparently has features that the version from Arch's
mkinitcpio-nfs-utils does not have. Fixes #75314.

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs