nvc0: fix dri3 prime buffer creation

We need to place shared buffers into GART.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
nv50: fix dri3 prime buffer creation

This is the same fix than
"nvc0: fix dri3 prime buffer creation"

Signed-off-by: Axel Davy <axel.davy@ens.fr>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>