drm/xe: Introduce xe_vma_op_prefetch_range struct for prefetch of ranges

drm/xe: Introduce xe_vma_op_prefetch_range struct for prefetch of ranges

Add xe_vma_op_prefetch_range struct for svm ranges prefetching, including
an xarray of SVM range pointers, range count, and target memory region.

-v2: Fix doc

Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Acked-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://lore.kernel.org/r/20250513040228.470682-2-himal.prasad.ghimiray@intel.com
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>