Simplify wake management code in keyguard.

Removes onWakeKey/Motion handling from keyguard since it's no longer used.
The legacy code was originally intended to have keyguard filter wake events
which is now done in PhoneWindowManager. Ultimately it just needs to call
PowerManager.wakeUp() since keyguard no longer filters these keys.

Change-Id: I5b8ef9b422abf850a85b57f21944e5eb09fbedc2