USB: AppOps: always show "USB connection" when usb connected

If no mode is choosen, "USB computer connection" will be hidden.
Unfortunately, there is no default mode, so users can't find it
by drag down statusbar. For better user experience, we export it
to users when usb connected.

Change-Id: I486e1a012f12f81f5a79d5f3686db58f980c0890