pinctrl: berlin: fix memory leak in berlin_pinctrl_build_state()

pinctrl: berlin: fix memory leak in berlin_pinctrl_build_state()

In the original implementation, krealloc() failure handling incorrectly
assigned the original memory pointer to NULL after kfree(), causing a
memory leak when reallocation failed.

Fixes: de845036f997 ("pinctrl: berlin: fix error return code of berlin_pinctrl_build_state()")
Signed-off-by: Yuan Chen <chenyuan@kylinos.cn>
Link: https://lore.kernel.org/20250620015343.21494-1-chenyuan_fl@163.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>