xhci: xhci debugfs device nodes weren't removed after device plugged out

There is a bug after plugged out USB device, the device and its ep00
nodes are still kept, we need to remove the nodes in xhci_free_dev when
USB device is plugged out.

Fixes: 052f71e2 ("xhci: Fix xhci debugfs NULL pointer dereference in resume from hibernate")
Cc: <stable@vger.kernel.org> # v4.15
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>