drm/nouveau/kms/nv50-: Log SOR/PIOR caps

Since I'm almost certain I didn't get capability checking right for
pre-volta chipsets, let's start logging any caps we find to make things
like this obvious in the future.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>