gpio: latch: use lock guards

gpio: latch: use lock guards

Use lock guards from linux/cleanup.h. This will make the subsequent
commit that switches to using value returning GPIO line setters much
simpler as we'll be able to return values without caring about releasing
the locks.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250220-gpio-set-retval-v2-12-bc4cfd38dae3@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>