drm/ttm: call driver move_notify() when doing system->tt bo moves

drm/ttm: call driver move_notify() when doing system->tt bo moves

Nouveau doesn't have enough information at ttm_backend_func.bind() time
to implement things like tiled GART, or to keep a buffer at a constant
address in the GPU virtual address space no matter where in physical
memory it's placed.

To resolve this, nouveau will handle binding of all buffers to the GPU
itself from the move_notify() hook.  This commit ensures it's called
for all buffer moves.

Talked to Dave about the impact on radeon, which uses move_notify, it
doesn't look like anything should break there.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Thomas Hellstrom <thomas@shipmail.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>