nouveau: nouveau_set_bo_placement takes TTM flags

commit c284815d upstream.

This seems to be wrong to me, spotted while thinking about dma-buf.

Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>