powerpc/powermac: of_node_put() is not needed after iterator

for_each_node_by_name() iterators only exit normally when the loop
cursor is NULL, So there is no need to call of_node_put().

Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>