buildRustPackage: remove unused arguments, minor styling changes

pkgs/build-support/rust/default.nix

@@ -1,17 +1,15 @@
-{ stdenv
-, lib
-, buildPackages
+{ lib
+, importCargoLock
+, fetchCargoTarball
+, rust
+, stdenv
+, callPackage
 , cacert
+, git
 , cargoBuildHook
 , cargoCheckHook
 , cargoInstallHook
 , cargoSetupHook
-, fetchCargoTarball
-, importCargoLock
-, rustPlatform
-, callPackage
-, git
-, rust
 , rustc
 , libiconv
 , windows
@@ -88,7 +86,7 @@ let
       (lib.removeSuffix ".json" (builtins.baseNameOf "${target}"))
     else target;
 
-  sysroot = (callPackage ./sysroot {}) {
+  sysroot = callPackage ./sysroot { } {
     inherit target shortTarget;
     RUSTFLAGS = args.RUSTFLAGS or "";
     originalCargoToml = src + /Cargo.toml; # profile info is later extracted