drm/xe/svm: Support DRM_XE_SVM_MEM_RANGE_ATTR_PAT memory attribute

This attributes sets the pat_index for the svm used vma range, which is
utilized to ascertain the coherence.

v2 (Matthew Brost)
- Pat index sanity check

Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250821173104.3030148-12-himal.prasad.ghimiray@intel.com


Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>