mm, numa: reclaim from all nodes within reclaim distance fix fix

mm, numa: reclaim from all nodes within reclaim distance fix fix

It's cleaner if the iteration is explicitly done only for NUMA kernels.
No functional change.

Intended to be folded into
mm-numa-reclaim-from-all-nodes-within-reclaim-distance.patch already in
-mm.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>