dmapool: add NUMA affinity support

dmapool: add NUMA affinity support

Introduce dma_pool_create_node(), like dma_pool_create() but taking an
additional NUMA node argument. Allocate struct dma_pool on the desired
node, and store the node on dma_pool for allocating struct dma_page.
Make dma_pool_create() an alias for dma_pool_create_node() with node set
to NUMA_NO_NODE.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>