power: supply: bq24190_charger: Turn off 5V boost regulator on shutdown

Turn off the 5V boost regulator on shutdown, there are 3 reasons for
doing this:

1. It drains he battery if left on
2. If left on the device will not charge when plugged into a charger
3. If left on and the powered peripheral attached to a Type-C port is
   removed before the next boot, then the Type-C port-controller will
   see VBus being present while nothing is attached confusing the
   TCPM state-machine.

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