gpio: acpi: Make acpi_gpio_count() take firmware node as a parameter

Make acpi_gpio_count() take firmware node as a parameter in order
to be aligned with other functions and decouple from unused device
pointer. The latter helps to create a common fwnode_gpio_count()
in the future.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>