power: smb5-lib: Improve the charge-termination WA handling

In rare scenarios when the battery enters/exits JEITA conditions
post termination, the termination workaround restarts thus
resetting the reference values. Improve this handling by
restarting the WA only if the existing WA timer is not running
thus avoiding WA restarts across minor JEITA oscillations.

Change-Id: I5bf91367b633abf79cbc60ef5bdf93cca9559022
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>