Disable the 5v boost converter on probe in case it was left on by
the BIOS, this fixes 2 problems:

1) This gets seen by the external battery charger as a valid Vbus
   supply and it then tries to feed Vsys from this creating a
   feedback loop which causes aprox. 300 mA extra battery drain
   (and unless we drive the external-charger-disable pin high it
   also tries to charge the battery causing even more feedback).
2) This gets seen by the pwrsrc block as a SDP USB Vbus supply

Since the external battery charger has its own 5v boost converter
which does not have these issues, we simply turn the separate
external 5v boost converter off and leave it off entirely.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>