of/base: release the node correctly in of_parse_phandle_with_args()

Call of_node_put() only when the out_args is NULL on success,
or the node's reference count will not be correct because the caller
will call of_node_put() again.

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>
[grant.likely: tightened up the patch]
Signed-off-by: Grant Likely <grant.likely@linaro.org>