poppy: Enable CONFIG_BATTERY_HW_PRESENT_CUSTOM
poppy: Enable CONFIG_BATTERY_HW_PRESENT_CUSTOM

Since poppy provides a custom battery present hw gpio, enable the
config option CONFIG_BATTERY_HW_PRESENT_CUSTOM.

BUG=b:65864825
BRANCH=None
TEST=Verified that when AC power is provided without battery present,
then EC auto powers up the AP. THis is essential for factory
testing. However, in order to make this work, CONFIG_SYSTEM_UNLOCKED
needs to be disabled. Verified device boots reliably after hardware
and software battery cutoff.

Change-Id: I9da1c68dfca3fd8c76570c78259adf42bf52522f
Signed-off-by: Furquan Shaikh <6be5c96c464778f89679b1062a2e0a6af93d2aa5@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/752686
Reviewed-by: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>

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