drm/radeon/kms: add new SI PCI ids

commit 7aaa61b3476462b69f1ac7669fcca8d608ce3cb5 upstream.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>