gpiolib: fix gpio_do_set_config()

Commit d90f3685 ("gpiolib: have a single place of calling
set_config()") introduced a regression where we don't pass the right
variable as argument to the set_config() callback of gpio driver from
gpio_set_config(). After reverting two additional patches that came
on top of it - this addresses the issue by changing the type of the last
argument of gpio_do_set_config() to unsigned long and making sure the
packed config variable is actually used in gpio_set_config().

Fixes: d90f3685 ("gpiolib: have a single place of calling set_config()")
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>