terraform-providers: limit subpackages

https://github.com/NixOS/nixpkgs/pull/52937#issuecomment-455629855

pkgs/applications/networking/cluster/terraform-providers/default.nix

@@ -11,10 +11,12 @@ let
       inherit (data) owner repo version sha256;
       name = "${repo}-${version}";
       goPackagePath = "github.com/${owner}/${repo}";
+      subPackages = [ "." ];
       src = fetchFromGitHub {
         inherit owner repo sha256;
         rev = "v${version}";
       };
+      
 
       # Terraform allow checking the provider versions, but this breaks
       # if the versions are not provided via file paths.