sbs-battery: fix power status when battery charging near dry

POWER_SUPPLY_STATUS_NOT_CHARGING is used for AC connected, but
battery not charging (e.g. because battery temperature is out
of acceptable range).

When battery is charging near dry and BATTERY_FULL_DISCHARGED is set,
it is wrong to set as POWER_SUPPLY_STATUS_NOT_CHARGING.
Just use BATTERY_DISCHARGING to decide the power supply status is
discharging or charging.

Signed-off-by: YH Huang <yh.huang@mediatek.com>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>