ab8500-fg: Allow capacity to raise from 1% when charging

When battery capacity was going below 1% fg is not supposed
to report 0% unless we've got the LOW_BAT IRQ, no matter
what the FG-algorithm says. This made fg get stuck at 1% if
charger is connected when capacity is 1%.

Signed-off-by: Hakan BERG <hakan.berg@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Marcus COOPER <marcus.xm.cooper@stericsson.com>
Reviewed-by: Srinidhi KASAGAR <srinidhi.kasagar@stericsson.com>