Revert "doc: update Kernel documentation build system"

Unfortunately we now see a number of now-fatal warnings about duplicate
labels.  It is often unclear how best to re-write the document in
question to not duplicate these otherwise logical headings.

This reverts commit 10a1df3cd43ba2fe893d5dd1aeb2e7109ef0007f.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/doc/sphinx/load_config.py b/doc/sphinx/load_config.py
index eeb394b..301a21a 100644
--- a/doc/sphinx/load_config.py
+++ b/doc/sphinx/load_config.py
@@ -21,29 +21,6 @@
         and os.path.normpath(namespace["__file__"]) != os.path.normpath(config_file) ):
         config_file = os.path.abspath(config_file)
 
-        # Let's avoid one conf.py file just due to latex_documents
-        start = config_file.find('Documentation/')
-        if start >= 0:
-            start = config_file.find('/', start + 1)
-
-        end = config_file.rfind('/')
-        if start >= 0 and end > 0:
-            dir = config_file[start + 1:end]
-
-            print("source directory: %s" % dir)
-            new_latex_docs = []
-            latex_documents = namespace['latex_documents']
-
-            for l in latex_documents:
-                if l[0].find(dir + '/') == 0:
-                    has = True
-                    fn = l[0][len(dir) + 1:]
-                    new_latex_docs.append((fn, l[1], l[2], l[3], l[4]))
-                    break
-
-            namespace['latex_documents'] = new_latex_docs
-
-        # If there is an extra conf.py file, load it
         if os.path.isfile(config_file):
             sys.stdout.write("load additional sphinx-config: %s\n" % config_file)
             config = namespace.copy()
@@ -52,6 +29,4 @@
             del config['__file__']
             namespace.update(config)
         else:
-            config = namespace.copy()
-            config['tags'].add("subproject")
-            namespace.update(config)
+            sys.stderr.write("WARNING: additional sphinx-config not found: %s\n" % config_file)