ocpc: Check CFET status before changing VSYS
ocpc: Check CFET status before changing VSYS

If the CFET is disabled, then the charging feedback loop is broken and
any further adjustments of VSYS will have no effect on the charging
current.  Therefore, the system should not try to make any VSYS
adjustments while this is occurring.

This commit causes the the OCPC loop to check if the CFET is disabled
before deciding to adjust VSYS or not.

BUG=b:160918663
BRANCH=None
TEST=Build and flash waddledee, charge DUT thru sub board until
battery toggles the CFET, wait until the toggling ceases, verify that
VSYS was not changed during that time.

Signed-off-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@google.com>
Change-Id: I7c0e5dce277118600b8f3120a6637938645db6ec
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2370044
Commit-Queue: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>
Tested-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>
Auto-Submit: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>
Reviewed-by: Diana Z <cb2016afc7183e5356c690dc63b4ba817470501a@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec