[media] extended-controls.rst: fix a build warning

/devel/v4l/patchwork/Documentation/media/uapi/v4l/extended-controls.rst:2116: WARNING: Inline literal start-string without end-string.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/uapi/v4l/extended-controls.rst

@@ -2112,7 +2112,7 @@ enum v4l2_mpeg_video_h264_sei_fp_arrangement_type -
 
 .. _v4l2-mpeg-video-h264-fmo-map-type:
 
-``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE`` ````
+``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE``
    (enum)
 
 enum v4l2_mpeg_video_h264_fmo_map_type -