Hide power menu from secure lockscreen (1/2)

- Use the same logic in our NavRing targets since crDroid allow power menu option through it

Special thanks to @cmorlok in this commit: https://github.com/omnirom/android_frameworks_base/commit/8f955b51a5f53d6b67cb1ec4fc34f07042766e0a and @Mahdi-Rom in this commit: https://github.com/Mahdi-Rom/android_frameworks_base/commit/c50cd9e53abbf571d090842fdb5b955e2c40a640

Change-Id: I9966f8282b4761a3ab154f63c8582a83a31dc5da