migration/bg-snapshot: Do not check for SKIP in iterator It's not possible to happen in bg-snapshot case. Reviewed-by: Juraj Marcin <jmarcin@redhat.com> Link: https://lore.kernel.org/r/20250613140801.474264-5-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Fabiano Rosas <farosas@suse.de>