In some rare cases, the drm_mm node cannot be removed synchronously
due to runtime PM conditions. In this situation, the node removal will
be delegated to a workqueue that will be able to wake up the device
before removing the node.

However, in this situation, the lifetime of the xe_ggtt_node cannot
be restricted to the lifetime of the parent object. So, this patch
introduces the infrastructure so the xe_ggtt_node struct can be
allocated in advance and freed when needed.

By having the ggtt backpointer, it also ensure that the init function
is always called before any attempt to insert or reserve the node
in the GGTT.

v2: s/xe_ggtt_node_force_fini/xe_ggtt_node_fini and use it
    internaly (Brost)
v3: - Use GF_NOFS for node allocation (CI)
    - Avoid ggtt argument, now that we have it inside the node (Lucas)
    - Fix some missed fini cases (CI)
v4: - Fix SRIOV critical case where config->ggtt_region was
      lost (Michal)
    - Avoid ggtt argument also on removal (missed case on v3) (Michal)
    - Remove useless checks (Michal)
    - Return 0 instead of negative errno on a u32 addr. (Michal)
    - s/xe_ggtt_assign/xe_ggtt_node_assign for coherence, while we
      are touching it (Michal)
v5: - Fix VFs' ggtt_balloon

Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240821193842.352557-11-rodrigo.vivi@intel.comSigned-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>