nid may be equal to NUMA_NO_NODE=-1.  Prevent accessing node_data array by
invalid index with check for nid.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Link: https://lkml.kernel.org/r/20240606080659.18525-1-abelova@astralinux.ru
Fixes: e83a437f ("mm/memory_hotplug: introduce "auto-movable" online policy")
Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>