init: Create /dev/bus/usb directory on boot

Create /dev/bus/usb directory on boot.  This allows modules
(such as USB host manager service) to watch changes directly
in /dev/bus/usb without having to look incrementally for
changes to /dev -> /dev/bus -> /dev/bus/usb.

Change-Id: If11e2fd975af1c0e8a886c4c88e976b468311934
Merge "init: Create /dev/bus/usb directory on boot"
Merge "Merge "init: Create /dev/bus/usb directory on boot""