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>

drivers/usb/core/hcd.h

@@ -51,6 +51,12 @@
  *
  * Since "struct usb_bus" is so thin, you can't share much code in it.
  * This framework is a layer over that, and should be more sharable.
+ *
+ * @authorized_default: Specifies if new devices are authorized to
+ *                      connect by default or they require explicit
+ *                      user space authorization; this bit is settable
+ *                      through /sys/class/usb_host/X/authorized_default.
+ *                      For the rest is RO, so we don't lock to r/w it.
  */
 
 /*-------------------------------------------------------------------------*/
@@ -90,6 +96,7 @@ struct usb_hcd {
 	unsigned		poll_rh:1;	/* poll for rh status? */
 	unsigned		poll_pending:1;	/* status has changed? */
 	unsigned		wireless:1;	/* Wireless USB HCD */
+	unsigned		authorized_default:1;
 
 	int			irq;		/* irq allocated */
 	void __iomem		*regs;		/* device memory/io */