power: supply: bq24190_charger: Add input_current_limit property

Export the input current limit of the charger as a
POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT property on the charger
power_supply class device.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>