usb: xhci: Fix memory leak in xhci_endpoint_reset()

If td_list is not empty the cfg_cmd will not be freed,
call xhci_free_command to free it.

Signed-off-by: Zheng Xiaowei <zhengxiaowei@ruijie.com.cn>
Cc: <stable@vger.kernel.org>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>