poppy: Add CONFIG_BATTERY_PRESENT_CUSTOM option
poppy: Add CONFIG_BATTERY_PRESENT_CUSTOM option

We define battery_is_present in board/poppy/battery.c, so we should
also set CONFIG_BATTERY_PRESENT_CUSTOM.

BRANCH=none
BUG=b:67984464
TEST=Flash soraka, battery status when connected and disconnected is correct.
TEST=Recovery from battery-cutoff is fine
TEST=Device does not get stuck in reboot loop when in critical battery
     condition

Change-Id: I02a597e30513a1bb4dab86a21ea107fc4876a63b
Signed-off-by: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/727444
Reviewed-by: Furquan Shaikh <6be5c96c464778f89679b1062a2e0a6af93d2aa5@chromium.org>

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