usb: add xen pvUSB backend, add num-ports check to ohci.
# gpg: Signature made Mon 23 May 2016 14:02:25 BST using RSA key ID
D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg: aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg: aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
* remotes/kraxel/tags/pull-usb-
20160523-1:
usb/ohci: Fix crash with when specifying too many num-ports
xen: add pvUSB backend
xen: write information about supported backends
xen: introduce dummy system device
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>