migration: Use error_propagate() in migrate_error_propagate() It improves readability, as suggested by Markus. Suggested-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Link: https://lore.kernel.org/r/20251202175317.1186544-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com>