Revert "remove longpress back to kill from dev settings for devicekeys == 0"

Because I say so.
And because someone without hardware keys might want to un-check this box EVER.

DON'T WHINE. THANKS

This reverts commit 3000a5d490d968639bc41401b4264cd56d9a2410.

Change-Id: If4e81660a9cb788bb0ec337838be6775fcd2a2b6