oak: make sure power button is stable when waiting for release
oak: make sure power button is stable when waiting for release

The debounce timer might be too slow to actually update the state of
debounced_power_pressed by the time we do power_button_is_pressed in
the S3->S5 state transition.
Call power_button_wait_for_release() instead of wait_for_power_button_release()
to make sure there are no deferred actions.

BRANCH=none
BUG=chrome-os-partner:50362, chrome-os-partner:51109
TEST=During dev mode screen, press power button, note the device stays off
TEST=sudo test_that -b oak <DUT_IP> firmware_FwScreenPressPower

Change-Id: Ic60c1847ba461ef874dea5bf7d03675622f24beb
Signed-off-by: YH Huang <d2b6e71fb6119e288e33a854f7510c1046bfaea5@mediatek.com>
Reviewed-on: https://chromium-review.googlesource.com/332310
Reviewed-by: Rong Chang <3a05493f7adfb36d203f663b3bc2ba30e9d6284f@chromium.org>

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