usb: add the concept of default authorization to USB hosts

This introduces /sys/bus/devices/usb*/authorized_default; it dictates
what is going to be the default authorization state for devices
connected to the host. User space can set that using the sysfs file.

We hook to the root hub instead of to the device controller as it is
quite easy to get to it in sysfs from the device structure (device
5-4.3 is usb5) vs. backtracking to the controller device.

By default it is set to be 'authorized' (!0) for normal, wired USB
devices and 'unauthorized' (0) for Wireless USB devices.

As suggested by Adrian Bunk, make authorized_default static

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>