staging: greybus: use new GPIO line value setter callbacks

staging: greybus: 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 driver to using
them.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Alex Elder <elder@riscstar.com>
Reviewed-by: Rui Miguel Silva <rui.silva@linaro.org>
Link: https://lore.kernel.org/r/20250407-gpiochip-set-rv-greybus-v1-1-9d4f721db7ca@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>