devm_memremap_pages: use numa_mem_id

Hint to closest numa node for the placement of newly allocated pages.
As that is where the device's other allocations will originate by
default when it does not specify a NUMA node.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NTejun Heo <tj@kernel.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

kernel/memremap.c

@@ -174,7 +174,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res)
 
 	nid = dev_to_node(dev);
 	if (nid < 0)
-		nid = 0;
+		nid = numa_mem_id();
 
 	error = arch_add_memory(nid, res->start, resource_size(res), true);
 	if (error) {