Users can use '-N' option to disable shutdown notification for faster shutdown process. Change-Id: I227dc4da3aa2f89d23f9b235e979cb6d3e25d635 Signed-off-by: Changpeng Liu <changpeng.liu@intel.com> Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/463950 Tested-by: SPDK CI Jenkins <sys_sgci@intel.com> Reviewed-by: Jim Harris <james.r.harris@intel.com> Reviewed-by: Ben Walker <benjamin.walker@intel.com>