x86: fix warning about nodeid

Impact: cleanup

Ingo found there warning about nodeid with some configs.

try to use for_each_online_node for non numa too. in that case
nodeid will be 0.

also move out boundary checking from setup_node_bootmem(), so
non-numa config will not check it.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <49B03069.80001@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>