veyron: enable low power idle
veyron: enable low power idle

Enable low power idle for veyron (with uart wakeup as well).
Low power idle is only active in S5/S3.

Also sorted options from board.h

BUG=chrome-os-partner:31226
BRANCH=none
TEST=load onto pinky-proto1, use idlestats command to verify that we are going
into deep sleep (STOP mode). Run 30 min. and verify no watchdog reboots or
anything out of ordinary.

Change-Id: Id14b04f33ea46b1e6cca1c8e812b5875e9ee0446
Signed-off-by: Alexandru M Stan <1784cbba6d7675b1eba55eaefe41c7672ad9da3b@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/219044
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

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