usbip: list: don't list devices attached to vhci_hcd

usbip host lists devices attached to vhci_hcd on the same server
when user does attach over localhost or specifies the server as the
remote.

usbip attach -r localhost -b busid
or
usbip attach -r servername (or server IP)

Fix it to check and not list devices that are attached to vhci_hcd.

Cc: stable@vger.kernel.org
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>