PowerMenu : Improve keyguard filtered actions

Replaces the check for visibility of lockscreen with the state
of the keyguard instead. This avoids the situation where actions
returning false from showDuringKeyguard, are still shown if user enters
emergency call screen.

Change-Id: Idb5df14813d9479bd4178dbb9eb3b91cbecda5de

Conflicts:

	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java