treewide: Remove usage of remaining redundant platform compatability stuff

Want to get this out of here for 18.09, so it can be deprecated
thereafter.

pkgs/os-specific/linux/systemd/default.nix

@@ -8,7 +8,6 @@
 , ninja, meson, python3Packages, glibcLocales
 , patchelf
 , getent
-, hostPlatform
 , buildPackages
 , withSelinux ? false, libselinux
 , withLibseccomp ? libseccomp.meta.available, libseccomp
@@ -79,7 +78,7 @@ in stdenv.mkDerivation rec {
     "-Dsystem-gid-max=499"
     # "-Dtime-epoch=1"
 
-    (if stdenv.isAarch32 || stdenv.isAarch64 || !hostPlatform.isEfi then "-Dgnu-efi=false" else "-Dgnu-efi=true")
+    (if stdenv.isAarch32 || stdenv.isAarch64 || !stdenv.hostPlatform.isEfi then "-Dgnu-efi=false" else "-Dgnu-efi=true")
     "-Defi-libdir=${toString gnu-efi}/lib"
     "-Defi-includedir=${toString gnu-efi}/include/efi"
     "-Defi-ldsdir=${toString gnu-efi}/lib"