linux-next: build failure after merge of the nvdimm tree

Hi Dan,

After merging the nvdimm tree, today's linux-next build (x86_64
allmodconfig) failed like this:

ERROR: "of_node_to_nid" [drivers/nvdimm/of_pmem.ko] undefined!

Caused by commit

  717197608952 ("libnvdimm: Add device-tree based driver")

X86 seems to not have a version of of_node_to_nid() even though CONFIG_OF
and CONFIG_NUMA are both 'y' in this build.

I have used the nvdimm tree from next-20180406 for today.

-- 
Cheers,
Stephen Rothwell