[media] DocBook: various version/copyright year updates

- update 2011 to 2012 for copyrights
- update V4L2 spec version to 3.6
- update the intro to also refer to part four: the Media Controller
- fix an incorrect revision section
- fix an incorrect 3.6 kernel changes section

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>