mm: remove unnecessary reclaimability check from NUMA balancing target

NUMA balancing already checks the watermarks of the target node to
decide whether it's a suitable balancing target.  Whether the node is
reclaimable or not is irrelevant when we don't intend to reclaim.

Link: http://lkml.kernel.org/r/20170228214007.5621-5-hannes@cmpxchg.org


Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jia He <hejianet@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>