Documentation/sphinx: Fix Directive import error

Sphinx 1.7 removed sphinx.util.compat.Directive so people
who have upgraded cannot build the documentation.  Switch to
docutils.parsers.rst.Directive which has been available since
docutils 0.5 released in 2009.

Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1083694


Co-developed-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/sphinx/kerneldoc.py

@@ -36,8 +36,7 @@ import glob
 
 from docutils import nodes, statemachine
 from docutils.statemachine import ViewList
-from docutils.parsers.rst import directives
-from sphinx.util.compat import Directive
+from docutils.parsers.rst import directives, Directive
 from sphinx.ext.autodoc import AutodocReporter
 
 __version__  = '1.0'