media: get rid of a new bogus Sphinx 1.5 warning

Documentation/media/uapi/cec/cec-api.rst:17: WARNING: uapi/cec/cec-funcs is already assigned section numbers (nested numbered toctree?)
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/cec/cec-funcs.rst

@@ -7,7 +7,6 @@ Function Reference
 
 .. toctree::
     :maxdepth: 1
-    :numbered:
 
     cec-func-open
     cec-func-close