hwmon: (tmp421) Add of_node_put() before return

Fix following coccicheck warning:
./drivers/hwmon/tmp421.c:416:1-23: WARNING: Function
for_each_child_of_node should have of_node_put() before return.

Early exits from for_each_child_of_node should decrement the
node reference counter.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20211018121538.16482-1-wanjiabing@vivo.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>