power: linear-charger: Report the correct battery status at SOC=0

Userspace initiates a shutdown if battery_status != charging
and SOC = 0, this is to prevent a deep-discharge of the battery
when the discharge current is higher than the charge current
at SOC = 0. Report this status from the kernel driver when
additionally the current voltage is below the cutoff threshold.

Change-Id: I89bb283ce9c0e01cd8c04cba2d7d33d5baca3fe7
Signed-off-by: Shilpa Suresh <sbsure@codeaurora.org>