pinctrl: th1520: Fix return value for unknown pin error

Fix th1520_pinctrl_dt_node_to_map() to set the return value before
jumping to free_configs when an unknown pin error occurs.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202410022336.xyWlV0Tf-lkp@intel.com/


Signed-off-by: Drew Fustini <dfustini@tenstorrent.com>
Link: https://lore.kernel.org/20241008-th1520-pinctrl-fixes-v3-1-5b60db446a49@tenstorrent.com


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