Cr50: Unlock console quickly when battery is unplugged
Cr50: Unlock console quickly when battery is unplugged

The assumption is that removing the cover and disconnecting the
battery is sufficiently obvious and time-consuming that it's not
necessary to sit there poking the power button repeatedly.

We still erase the NVMEM completely before unlocking, of course.

BUG=chrome-os-partner:55322
BRANCH=none
TEST=make buildall; test on Gru

Toggle the Cr50 console with "lock on", then "lock off". Confirm
that the 5-minute process only requires one poke when the battery
cable is disconnected. Also confirm that both ways abort if you don't
press the button at all.

Change-Id: Iaa0f5eb102b914c95f3a34002438cbe80affcfb5
Signed-off-by: Bill Richardson <129945214b1d548d8e49b6c29c43094f8c78057f@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/388879
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>

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