SystemUI: Add tunables for clock position

Author: LuK1337 <priv.luk@gmail.com>
Date:   Wed Aug 1 18:10:39 2018 +0200

    SystemUI: Initialize mClockVisibleByUser to android:visibility

    * Fixes ~ triple clock ~ after leaving from Google SUW.

    Change-Id: I3ceea4400b3057e2b6b1f221f9074b1d451133ea

Author: Luca Stefani <luca.stefani.ge1@gmail.com>
Date:   Sun Jul 29 14:19:08 2018 +0200

    SystemUI: Fix default clock blacklist value

    Change-Id: Ibdc4f6a707569ddb417854760cf579daca989ebb

Change-Id: Icdc039d13fd2676c1eb979a81fb77f9a6ec59b4a