gpiolib: acpi: Make acpi_gpio_to_gpiod_flags() usable for GpioInt()

GpioInt() implies input configuration of the pin. Add this to
the acpi_gpio_to_gpiod_flags() and make usable for GpioInt().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>