power: supply: bq24735-charger: Request status GPIO with initial input setup

This requests the status GPIO with initial input setup. It is required
to read the GPIO status at probe time and thus correctly avoid sending
I2C messages when AC is not plugged.

When requesting the GPIO without initial input setup, it always reads 0
which causes probe to fail as it assumes the charger is connected, sends
I2C messages and fails.

While at it, this switches the driver over to gpiod API.

Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: Sebastian Reichel <sre@kernel.org>