8042: Fix test_power_button
8042: Fix test_power_button

test_power_button was making some bad assumptions about the state
of keystroke enable. The power button also has a 100ms debounce time we
need to take into account, otherwise we will miss the event. This change
makes the test more robust.

BUG=b:242886255
BRANCH=none
TEST=run unit tests

Signed-off-by: Raul E Rangel <9a9c998e11a2655b1de9a05eeeef5f710c0dc7ed@chromium.org>
Change-Id: If10d690c3e96c9e21abee8046cdd13d86257e7f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3846282
Reviewed-by: Jeremy Bettis <4df7b5147fee087dca33c181f288ee7dbf56e022@chromium.org>

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