sonynwz: rework dualboot mechanism

Now boot to RB if play/pause is pressed during 1 second, and to OF if
back is pressed 1 second. Otherwise power off. If hold is on, also power
off. In USB and alarm context, always boot and back determines OF vs RB.

Change-Id: Ie1d6c971901d6473255461cc7d71a5ee3177ecad
3 files changed