drm/radeon: 9800 SE has only one quadpipe

Although these cards have 2 pipelines on the silicon only
the first passed the QA and the other should be disabled.

http://www.digital-daily.com/video/ati-radeon9800se/
http://www.rojakpot.com/showarticle.aspx?artno=101&pgno=1

agd5f: add some other SE cards as well; fix up kms

Signed-off-by: Tormod Volden <debian.tormod@gmail.com>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>