drm/xe: Restore system memory GGTT mappings

GGTT mappings reside on the device and this state is lost during suspend
/ d3cold thus this state must be restored resume regardless if the BO is
in system memory or VRAM.

v2:
 - Unnecessary parentheses around bo->placements[0] (Checkpatch)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241031182257.2949579-1-matthew.brost@intel.com