power: pm8921-bms: fix fake battery emulation

With the recent split of functions to calculate and report state of
charge, the faking battery feature broke, it remained in the calculate
function.

Move the fake battery feature in the reporting function, where it really
belongs.

Change-Id: I6a3fcc3b233792d87ea4ac8fe2e155e10ca24e21
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Neha Pandey <nehap@codeaurora.org>