Bug#864219: qemu: CVE-2017-9375: usb: xhci infinite recursive call via xhci_kick_ep

[Salvatore Bonaccorso]

Control: found -1 1:2.8+dfsg-6+deb9u2

This issue was addressed in 1:2.8+dfsg-6+deb9u1 though will be backed
out again in 1:2.8+dfsg-6+deb9u2 due to regression in the xhci area.
Adding thus a found version accordingly on 1:2.8+dfsg-6+deb9u2 already
(although the package has not yet been released from security.d.o).