drm/radeon/kms: remove the _DRM_DRIVER from the KMS paths.

This causes an issue since we fixed the drm mappings to do the right thing,
so its just a copy and pasto.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>