power: stc3117-battery: Fix minor bugs in FG calculations

Fix following bugs in FG code:
- change cc_adj/vm_adj to signed value
- update calculation for vm_cnf
- update soc correction calculation and enable it based on DT
  property.

While at it, also add 'soc-tbl' property which contains the SOC
points used for the SOC-OCV reference table in the hardware.

CRs-Fixed: 951248
Change-Id: Icc85f75b65e913f9f6bcf5e73abfd51ba42ad2c4
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>