G2: Add proximity wake flag

Change-Id: Ibd4dd080c27a983d9416d6abc42a8b7fc245bd85
Add ability to disable KnockOn
if a placeholder file named 'dt2woff' is present on /sdcard
this disables KnockOn

Change-Id: Ie3896ab251f53149948c157c340cd765f1bf5a15