power: qpnp-charger: fix chg done logic for dual charge path

When two chargers are connected simultaneously and one is
removed do not allow chg_done to be set to false. Charging
should only be reported to not be fully if charging is
resumed or both chargers have been removed.

Change-Id: Ic3e0bf244b89c81a66ec92cb641d8463055d959a
CRs-Fixed: 513398
Signed-off-by: David Keitel <dkeitel@codeaurora.org>