gpiolib: add support for pull up/down to lineevent_create

Add support for pull up/down to lineevent_create.
Use cases include receiving asynchronous presses from a
push button without an external pull up/down.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>