scst: Remove residual procfs code

Procfs support was removed in 2019, but dead configuration guards,
patch specialization logic and unused declarations remained. Remove these
remnants and simplify paths that can no longer receive procfs-only objects.

scripts/generate-kernel-patch

@@ -255,8 +255,6 @@ else
   scst_makefile="Makefile.scst"
 fi
 
-specialize_patch_options+=(-v "config_scst_proc_undefined=1")
-
 if [ "${debug_specialize}" = "true" ]; then
   specialize_patch_options+=(-v "debug=1")
 fi