libnvdimm: Remove unused nd_attach_ndns

nd_attach_ndns() hasn't been used since 2017's
commit 452bae0a ("libnvdimm: fix nvdimm_bus_lock() vs device_lock()
ordering")

Remove it.

Note the __ version is still used and has been left.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/20250220004538.84585-3-linux@treblig.org


Signed-off-by: Ira Weiny <ira.weiny@intel.com>