docs: Raise the minimum Sphinx requirement to 2.4.4

Commit 31abfdda65 (docs: Deprecate use of Sphinx < 2.4.x) in 6.2 added a
warning that support for older versions of Sphinx would be going away.
There have been no complaints, so the time has come.  Raise the minimum
Sphinx version to 2.4.4 and clean out some compatibility code that we no
longer need.

Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/874jgs47fq.fsf@meer.lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/sphinx/automarkup.py

@@ -7,11 +7,7 @@
 from docutils import nodes
 import sphinx
 from sphinx import addnodes
-if sphinx.version_info[0] < 2 or \
-   sphinx.version_info[0] == 2 and sphinx.version_info[1] < 1:
-    from sphinx.environment import NoUri
-else:
-    from sphinx.errors import NoUri
+from sphinx.errors import NoUri
 import re
 from itertools import chain
 

Documentation/sphinx/cdomain.py

@@ -127,11 +127,7 @@ def setup(app):
 
     # Handle easy Sphinx 3.1+ simple new tags: :c:expr and .. c:namespace::
     app.connect('source-read', c_markups)
-
-    if (major == 1 and minor < 8):
-        app.override_domain(CDomain)
-    else:
-        app.add_domain(CDomain, override=True)
+    app.add_domain(CDomain, override=True)
 
     return dict(
         version = __version__,

Documentation/sphinx/kfigure.py

@@ -61,13 +61,7 @@ import sphinx
 from sphinx.util.nodes import clean_astext
 import kernellog
 
-# Get Sphinx version
-major, minor, patch = sphinx.version_info[:3]
-if major == 1 and minor > 3:
-    # patches.Figure only landed in Sphinx 1.4
-    from sphinx.directives.patches import Figure  # pylint: disable=C0413
-else:
-    Figure = images.Figure
+Figure = images.Figure
 
 __version__  = '1.0.0'