pinctrl: stm32: add missing of_node_put

Fix OF node leaks by calling of_node_put in
for_each_available_child_of_node when the cycle returns.

Generated by: scripts/coccinelle/iterators/for_each_child.cocci

Signed-off-by: Junlin Yang <yangjunlin@yulong.com>
Link: https://lore.kernel.org/r/20210215103643.898-1-angkery@163.com


Acked-by: Fabien Dessenne <fabien.dessenne@foss.st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>