power: qpnp-charger: don't force on BATFET in some cases

For the case where battery presence detection has
determined that the battery is not present,
do not allow software to force the SMBB
to only draw current from the battery.

Change-Id: I1e09f51e9f022368351e672ac0ceb0069392fc28
Signed-off-by: David Keitel <dkeitel@codeaurora.org>