Documentation/dontdiff: add further autogenerated files to ignore list

Mainly resulting from (but not limited to) autogenerated files of
lib/raid6 and drivers/gpu/drm/radeon. List generated as result of
a diff of a clean 2.6.36 tree against a built one.

Signed-off-by: Michael Prokop <mika@grml.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>