smb-lib: fix slave BCL for HVDCP3

Currently, fixed 5V adapter voltage is used for calculating slave FCC.
When HVDCP 3.0 is used it skews the desired FCC distribution. Fix this
by using the HVDCP3 pulse count to determine the actual adapter voltage
when limiting the slave battery current.

Change-Id: Ib4735ffe7b6287a3e57e0f74eb24c13c6a2b7a5a
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>
Signed-off-by: Nicholas Troast <ntroast@codeaurora.org>