gpio: reg: use new GPIO line value setter callbacks

gpio: reg: use new GPIO line value setter callbacks

struct gpio_chip now has callbacks for setting line values that return
an integer, allowing to indicate failures. Convert the legacy generic
gpio-reg module to using them. We have to update the two legacy ARM
platforms that use it at the same time as they call the set_multiple()
callbacks directly (they shouldn't but it's old technical debt I
suppose).

Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250623-gpiochip-set-rv-gpio-v3-1-90f0e170a846@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>