drm/radeon/kms: add rn50/r100/r200 CS tracker.

This adds the command stream checker for the RN50, R100 and R200 cards.

It stops any access to 3D registers on RN50, and does checks
on buffer sizes on the r100/r200 cards. It also fixes some texture
sizing checks on r300.

Signed-off-by: Dave Airlie <airlied@redhat.com>