power: pm8921-charger: use SoC % value for charging stop and resume

Current pm8921 charger code doesn't consider the SoC % to determine
end of charging and recharging state. This can cause weird UI display
on SoC % and charging state.
For example, charging is completed when SoC % is not reached 100% or
charging is not completed even if SoC % is already 100%.
So this patch change how to determine end of charging and recharging.

Change-Id: Ice658488744d71117fedb64e0fa0eb7ad34c6573