Fix possible NPE + and missing expandable panel

Steps to reproduce for NPE:
- go into volume style settings
- switch to disabled
- switch to expanded
- NPE and hotreboot

Fix:
Check if mStreamControls is initialized and if not lock it and do it.

Steps for expandable error:
- go into volume style settings
- switch to disable
- press one time the volume button
- change to expandable
- change the volume and press the expanded icon
- result is it does not expand and is empty due of the missing volume panels.

Fix:
- if it was changed from disabled to expanded be sure that the additional volume panels
are recreated.
SystemUI: Set Status bar opaque during drawer pulldown on tablets only

The status bar only needs to be set as opaque when the notification drawer is pulled down on 600dp and 720dp devices. On phones, this is unnecessary as the top header of the drawer covers the status bar on the phone UI. This change makes a huge difference in reponsiveness on devices that run the phone UI as there is no longer a delay before the drawer appears when interacting with it on an activity with transclucent window decor.