power: qpnp-charger: report trickle charging correctly

When trickle charging the battery FET is off. Fix
the charging report logic to address this and
correctly report the trickle charging status.

Change-Id: I46a13c219e8147e36f8bf3fd749b496c0af9ca11
CRs-Fixed: 587259
Signed-off-by: David Keitel <dkeitel@codeaurora.org>