nvme: avoid crashes when node 0 is memoryless node.

When CONFIG_NUMA is enabled and node 0 is memoryless, the system
crashes because nvme_probe() sets the device->numa_node to 0 by
set_dev_node(&pdev->dev, 0), so it tries to allocate memory from node 0.
To avoid the crash, we should change the 0 to first_memory_node.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>