usb: Fix iovec memleak on combined-packet free

Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/usb/combined-packet.c

@@ -39,6 +39,7 @@ static void usb_combined_packet_remove(USBCombinedPacket *combined,
     p->combined = NULL;
     QTAILQ_REMOVE(&combined->packets, p, combined_entry);
     if (QTAILQ_EMPTY(&combined->packets)) {
+        qemu_iovec_destroy(&combined->iov);
         g_free(combined);
     }
 }