drm/nouveau: allow cursor image and position to survive suspend

- This isn't triggered yet on a normal kernel, because it still does a VT
switch, but it seemed like a good idea to fix this now.

Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Maarten Maathuis <madman2003@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>