Revert "Revert "Lockscreen Blur""

We want to keep this.
This reverts commit dc82b58247e4946acd8ae497a65fd79b0b61ebb9.

Conflicts:
	packages/Keyguard/src/com/android/keyguard/KeyguardViewManager.java
	services/java/com/android/server/power/DisplayPowerController.java
Fix lockscreen blur on xxhdpi devices (thanks @Curtis Mayers)

All credits to Curtis Mayers: https://gerrit.paranoidandroid.co/#/c/382/