gpioset: fix help text
gpioset: fix help text

Signed-off-by: Bartosz Golaszewski <108de5fbc428215dc26df4468b48691526611148@gmail.com>

brgl/libgpiod,brgl/libgpiod,brgl/libgpiod,clemensg/libgpiod,brgl/libgpiod,clemensg/libgpiod