power: pm8921-bms: adjust battery tolerances based on charging state

Some board designs have grounding issues where current flows from
external common ground instead of the rsense resistor. This is typically
seen on a fake battery power supply setup which also has another device
(such as a callbox) connected to the system ground. IOW the gnd of the
power supply and the ground of the callbox are same and the current flows
from this common ground instead of rsense.

This causes the BMS to see incorrect battery current direction, it thinks
the battery is being charged and moves to a high load state. It recovers
after a while to move back in to low load state. This transition continues
causing irregular increase in sleep current.

Fix this by increasing the battery tolerance while not charging.

CRs-Fixed: 337827
Change-Id: I824387568e93191365faead05a70850f0eed423d
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>