qcom: battery: Fix parallel disabled issue on charging boot

Parallel algorithm votes to disable slave charger if
devices boot with charger attached, caused by a default
taper_pct = 0 value which leaves slave's FCC share to 0.

Fix it by initializing taper_pct with 100.

Change-Id: Ia03755d3abf389017c1b7e808eff53b5f1761e65
Signed-off-by: Harry Yang <harryy@codeaurora.org>