pinctrl: th1520: Convert dt child node loop to scoped iterator

Convert th1520_pinctrl_dt_node_to_map() to use a scoped iterator with
for_each_available_child_of_node_scoped(). As a result, there is no need
to call of_node_put() anymore. The put_child label has been renamed to
free_map which is now a more accurate description.

Suggested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Drew Fustini <dfustini@tenstorrent.com>
Link: https://lore.kernel.org/20241008-th1520-pinctrl-fixes-v3-3-5b60db446a49@tenstorrent.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>