power: qpnp-fg-gen3: Clear charge_full flag during discharging

When SOC is held @ 100% after charge termination, charge_full
flag is cleared only when the monotonic SOC drops below recharge
SOC threshold. This can cause the flag to be held for a long time
when the charger is removed. Fix this by clearing charge_full
flag when charging status had changed from FULL.

Change-Id: I35b52ddc45f314347f0e4d8433d5fb550663267c
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>