gpiofind: use gpiod_simple_find_line() internally
gpiofind: use gpiod_simple_find_line() internally

Switch to using the simple API in gpiofind.

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

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