of: dynamic: fix memory leak related to properties of __of_node_dup

If a node with no properties is dynamically added, then a property is
dynamically added to the node, then the property is dynamically removed,
the result will be node->properties == NULL and node->deadprops != NULL.

Add a separate function to release the properties in both lists.

Signed-off-by: Lixin Wang <alan.1.wang@nokia-sbell.com>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>