apparmor, virt-aa-helper: Allow access to /sys/bus/usb/devices

Required to generate correct profiles when using usb passthrough.

Bug-Ubuntu: https://bugs.launchpad.net/bugs/565691Signed-off-by: NStefan Bader <stefan.bader@canonical.com>
Signed-off-by: NChristian Ehrhardt <christian.ehrhardt@canonical.com>
Acked-by: NJamie Strandboge <jamie@ubuntu.com>
Acked-by: NIntrigeri <intrigeri@boum.org>

examples/apparmor/usr.lib.libvirt.virt-aa-helper

@@ -22,6 +22,7 @@ profile virt-aa-helper /usr/{lib,lib64}/libvirt/virt-aa-helper {
   # for hostdev
   /sys/devices/ r,
   /sys/devices/** r,
+  /sys/bus/usb/devices/ r,
   deny /dev/sd* r,
   deny /dev/vd* r,
   deny /dev/dm-* r,