eve: Disable discharge-on-ac with board 5+
eve: Disable discharge-on-ac with board 5+

Board version 5+ has BD99954 charger which does not have audible
noise when battery is full and charger is at 20V.  Disable the
discharge-on-ac workaround for these boards.

BUG=b:37228827
BRANCH=none
TEST=tested on board version 5 that discharge-on-ac is not enabled
when the battery is full.

Change-Id: I72e6870e06328d84a802c2f736659677de1f9a08
Signed-off-by: Duncan Laurie <70662b43bc1a20b57ded72a2b08be88dd0da4841@google.com>
Reviewed-on: https://chromium-review.googlesource.com/524222
Reviewed-by: Scott Collyer <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@chromium.org>

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