power: smb1351: report real fastchg current

Report the real set fast charge current through the power supply
framework in order to allow the primary charge to better optimize
current distributions.

CRs-Fixed: 930588
Change-Id: Ia0bbcfb91482bd47bab01e5fdaf29e5ea55d7b97
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>