qcom: battery: Remove SMB taper reduction from overall FCC

During parallel charging, once PMI hits taper mode, SMB's share of FCC
is reduced by 25% and the amount of reduction is shifted over to PMI.

This is not supposed to happen when PMI's current is also reduced in
thermal condition.

The change is remove SMB taper FCC reduction from overall FCC. Also
decrease step size from 25% to 10%.

Change-Id: I8c5ad15a95643916476f0479b37e9e54610663cb
Signed-off-by: Harry Yang <harryy@codeaurora.org>