power: qpnp-fg-gen4: Fix maintenance SOC reporting logic

Some times the SOC value reported as increasing even though
there is no charger connected to the device. Fix it by correcting
maintenance SOC reporting logic.

Change-Id: I0fb897616c72467f68b9be9a193c28a9008765ea
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>