drm/xe: Memory allocations are tile-based, not GT-based

Since memory and address spaces are a tile concept rather than a GT
concept, we need to plumb tile-based handling through lots of
memory-related code.

Note that one remaining shortcoming here that will need to be addressed
before media GT support can be re-enabled is that although the address
space is shared between a tile's GTs, each GT caches the PTEs
independently in their own TLB and thus TLB invalidation should be
handled at the GT level.

v2:
 - Fix kunit test build.

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230601215244.678611-13-matthew.d.roper@intel.com


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