extcon: int3496: Use gpiod_get instead of gpiod_get_index

Now that we've an acpi mapping table we should be using gpiod_get
instead of gpiod_get_index.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>