drm/radeon/kms: fix display bandwidth setup on rs4xx

I missed rs4xx in 7f1e613daf0fdd0884316ab25a749db3c671329e

Fixes fdo bug 27219.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
1 file changed