gpiolib: acpi: Change type of dflags

Most of the code inside GPIO library is using enum gpiod_flags.
Some of the function still operate with unsigned int.

In order to be more consistent and better type checking, convert
acpi_gpiochip_parse_own_gpio() to use enum gpiod_flags instead of
unsigned int.

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