drm/nouveau/uvmm: Allow larger pages

drm/nouveau/uvmm: Allow larger pages

Now that everything in UVMM knows about the variable page shift, we can
select larger values.

The proposed approach relies on nouveau_bo::page unless if it would cause
alignment issues (in which case we fall back to searching for an
appropriate shift)

Signed-off-by: Mary Guillemard <mary@mary.zone>
Co-developed-by: Mohamed Ahmed <mohamedahmedegypt2001@gmail.com>
Signed-off-by: Mohamed Ahmed <mohamedahmedegypt2001@gmail.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: James Jones <jajones@nvidia.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patch.msgid.link/20251110-nouveau-compv6-v6-2-83b05475f57c@mary.zone