[PATCH] document DRM ioctl use

Document DRM's usage of 'd' as its ioctl identifier.  This can't be
changed, it is in every X server.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/ioctl-number.txt

@@ -117,6 +117,7 @@ Code	Seq#	Include File		Comments
 					<mailto:natalia@nikhefk.nikhef.nl>
 'c'	00-7F	linux/comstats.h	conflict!
 'c'	00-7F	linux/coda.h		conflict!
+'d'	00-FF	linux/char/drm/drm/h	conflict!
 'd'	00-1F	linux/devfs_fs.h	conflict!
 'd'	00-DF	linux/video_decoder.h	conflict!
 'd'	F0-FF	linux/digi1.h