drm/xe/migrate: Add function to copy of VRAM data in chunks

drm/xe/migrate: Add function to copy of VRAM data in chunks

Introduce a new function to copy data between VRAM and sysmem objects.
The existing xe_migrate_copy() is tailored for eviction and restore
operations, which involves additional logic and operates on entire
objects.
The xe_migrate_vram_copy_chunk() allows copying chunks of data to or
from a dedicated buffer object, which is essential in case of VF
migration.

Signed-off-by: Lukasz Laguna <lukasz.laguna@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251112132220.516975-22-michal.winiarski@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>