of: fix "/cpus" reference leak in of_numa_parse_cpu_nodes()

The call to of_find_node_by_path("/cpus") returns the cpus device_node
with its reference count incremented. There is no matching of_node_put()
call in of_numa_parse_cpu_nodes() which results in a leaked reference
to the "/cpus" node.

This patch adds an of_node_put() to release the reference.

fixes: 298535c0 ("of, numa: Add NUMA of binding implementation.")
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Rob Herring <robh@kernel.org>