BluetoothManagerService: fix enabling/disabling BT from Quictsettings under second user,

Change-Id: I8173559b2c734968ef4a8d86fddaa3a73d5c2b1e
Remove the navigation camera icon in keyguard if disabled by DPM

The logic here is incorrect: the camera shortcut is/should be accessible
even with a secure lock screen. As a result, a device with the lock
screen camera disabled by DPM and an insecure lock screen would still
display the unfunctional shortcut.

Change-Id: If1d172932c6c2af596c38e623521c992fdf95402
Lockscreen Notifications: Fix possible NPE