drm/nouveau/gsp: support deeper page tables in COPY_SERVER_RESERVED_PDES

Use data from 'struct nvkm_vmm_page/desc' to determine which PDEs need
to be mirrored to RM instead of hardcoded values for pre-Hopper page
tables.

Needed to support Hopper/Blackwell.

Signed-off-by: Ben Skeggs <bskeggs@nvidia.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Timur Tabi <ttabi@nvidia.com>
Tested-by: Timur Tabi <ttabi@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>