drm/xe: Move GGTT from GT to tile

The GGTT exists at the tile level.  When a tile contains multiple GTs,
they share the same GGTT.

v2:
 - Include some changes that were mis-squashed into the VRAM patch.
   (Gustavo)

Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Acked-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://lore.kernel.org/r/20230601215244.678611-9-matthew.d.roper@intel.com


Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>