This prevents an endless stream of key repeats spamming the keyguard
if a volume key is pressed at the same time you turn off the screen
with the power button.
This is part of a fix for bug b/2198537
Change-Id: I0d7e335fee79cbebba96b2cd908458c3c94c839e
Signed-off-by: Mike Lockwood <lockwood@android.com>