mm/mempool.c: use kmalloc_array_node()

mm/mempool.c: use kmalloc_array_node()

Now that we have a NUMA-aware version of kmalloc_array() we can use it
instead of kmalloc_node() without an overflow check in the size
calculation.

Link: http://lkml.kernel.org/r/20170927082038.3782-6-jthumshirn@suse.de
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mike Marciniszyn <infinipath@intel.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>