usb: usbip tool: Fix refresh_imported_device_list()

The commit 0775a9cb ("usbip: vhci extension: modifications
to vhci driver") introduced multiple controllers, but the status
of the ports are only extracted from the first status file, fix it.

Reviewed-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>