Keyguard: LN: fix and harden against null pointer exceptions

Change-Id: Iff66791bb35b911e837b0a1747a72effdce507e3

Conflicts:
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java

Conflicts:
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java