drm/xe: Use the drm_pagemap_util helper to get a svm pagemap owner

drm/xe: Use the drm_pagemap_util helper to get a svm pagemap owner

Register a driver-wide owner list, provide a callback to identify
fast interconnects and use the drm_pagemap_util helper to allocate
or reuse a suitable owner struct. For now we consider pagemaps on
different tiles on the same device as having fast interconnect and
thus the same owner.

v2:
- Fix up the error onion unwind in xe_pagemap_create(). (Matt Brost)

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251219113320.183860-12-thomas.hellstrom@linux.intel.com