gpio: tps65912: check the return value of regmap_update_bits()

regmap_update_bits() can fail, check its return value like we do
elsewhere in the driver.

Link: https://lore.kernel.org/r/20250707-gpiochip-set-rv-gpio-round4-v1-2-35668aaaf6d2@linaro.org


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>