of_find_node_by_name() returns a node pointer with refcount
incremented, we should use of_node_put() on it when done.
Add missing of_node_put() to avoid refcount leak.

Fixes: e20db70d ("thermal: imx_sc: add i.MX system controller thermal support")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220517055121.18092-1-linmq006@gmail.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>