QA:Testcase Virtualization Hotplug USB device to guest

Setup

Prepare a machine to support vt-d, e.g. Dell 755.

How to test

1. Start a VM using virt-manager.
2. Check device using lspci, here we will hotplug network from host to guest:

   #lsusb

   ...

   Bus 002 Device 002: ID 0781:5151 SanDisk Corp. Cruzer Micro Flash Drive

   ...

3. Open a Virtual Machine->show details->Add Hardware->select 'USB Host Device' in hardware type list->select 002:002 in device list to assign the usb device to a vm.
4. In guest,  issue lsusb.

Expected Results

1. After step 4, #lsusb can find the hotpluged usb device