jf-common: translucent lockscreen decor

Original commit:
https://github.com/CyanogenMod/android_device_htc_m7-common/commit/0ba9dbb89160cd0fa25c88b6bba0f2b9bbfcd6b9

Change-Id: If98bdfb72dbcd2b896d9a2053a4b763cc1e049f0