QS: Revert change to when user switcher is shown

Its making it inconsistently show up on the lock screen. Until
final behavior is decided, revert to old behavior.

Change-Id: Ifc69f2d5b527cc9ce5a174b16b8b605db26fc35b
Fixes: 36141544
Test: visual

packages/SystemUI/src/com/android/systemui/statusbar/phone/MultiUserSwitch.java

@@ -74,7 +74,7 @@ public class MultiUserSwitch extends FrameLayout implements View.OnClickListener
         if (mUserListener == null) {
             return false;
         }
-        return mUserListener.getUserCount() > 1;
+        return mUserListener.getUserCount() != 0;
     }
 
     public void setUserSwitcherController(UserSwitcherController userSwitcherController) {