drm/xe/pf: Invalidate LMTT after completing changes

Once we finish populating all leaf pages in the VF's LMTT we should
make sure that hardware will not access any stale data. Explicitly
force LMTT invalidation (as it was already planned in the past).

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://lore.kernel.org/r/20250711193316.1920-7-michal.wajdeczko@intel.com