veyron_brain: Increase hold_pwr_button_poweroff time

Non-laptop Veyrons need to hold the power button for a time
determined by the RK808 PMIC (PWRON_LP_OFF_TIME) which is
6 seconds by default. We'll define hold_pwr_button_poweroff
as 7 seconds to give some margin.

BUG=chrome-os-partner:44275
BRANCH=firmware-veyron
TEST=FAFT runs on veyron_mickey now.
Signed-off-by: David Hendricks <dhendrix@chromium.org>

Change-Id: I5b91414bfe126fb5cd7101147d027d998cc9c7a2
Reviewed-on: https://chromium-review.googlesource.com/295188
Reviewed-by: Wai-Hong Tam <waihong@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>
Commit-Queue: David Hendricks <dhendrix@chromium.org>
1 file changed