drm/xe/svm: Refactor usage of drm_gpusvm* function in xe_svm

drm/xe/svm: Refactor usage of drm_gpusvm* function in xe_svm

Define xe_svm_range_find_or_insert function wrapping
drm_gpusvm_range_find_or_insert for reusing in prefetch.

Define xe_svm_range_get_pages function wrapping
drm_gpusvm_range_get_pages for reusing in prefetch.

-v2 pass pagefault defined drm_gpu_svm context as parameter
in xe_svm_range_find_or_insert(Matthew Brost)

Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Acked-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://lore.kernel.org/r/20250513040228.470682-10-himal.prasad.ghimiray@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>