power: qpnp-charger: IBAT calibration/re-trimming

1% of PM8941 devices have a IBAT_TRIM error, due to which
these parts may show IBAT_MAX out of spec. This can lead to
charging of the battery with higher current, thus degrading its
life.

Fix this by re-trimming IBAT_MAX using the below procedure. This
process needs to be carried out for every DCP insertion until
the TRIM_GOOD bit is set.

1. After AICL is complete, force IBAT_MAX to 500mA
2. If ibat_loop has triggered, read the battery current
3. Calculate the difference in the expected and observed current
4. Accordingly adjust IBAT_TRIM value
5. Set TRIM_GOOD bit if the trimming is successfull

CRs-Fixed: 561116
Change-Id: I239c0ea4510ffefbab86f43a3703e63868f19616
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>