iwd: drop systemd dep, not needed when specifying config flags too
iwd: drop systemd dep, not needed when specifying config flags too

Only used to guess if systemd-y bits should be installed,
which we manually specify already.  So drop unneeded dep.

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