drm/xe/migrate: Populate struct drm_pagemap_addr array

Workaround to ensure all addresses are populated in the array as
this is expected when creating the copy batch. This is required
because the migrate layer does not support 2MB GPU pages yet. A
proper fix will come in a follow-up.

Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250805140028.599361-6-francois.dugast@intel.com


Signed-off-by: Francois Dugast <francois.dugast@intel.com>