power: supply: bq24190_charger: Remove extcon handling

Now that drivers/i2c/busses/i2c-cht-wc.c uses
"input-current-limit-from-supplier" instead of "extcon-name" the last
user of the bq24190 extcon code is gone, remove it.

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