SystemUI: remove duplicate PhoneStatusBar variables

These variables are defined in the super class, BaseStatusBar. So
anything in BaseStatusBar that depends on these variables is always in
the wrong state because they are never updated properly.

This primarily fixes callbacks to IStatusBarService
onPanelRevealed() and onPanelHidden().

Change-Id: I0579c843c825f77278125e7d5059cd11e8576d29
Signed-off-by: Roman Birg <roman@cyngn.com>