A PERSISTENT RESERVE OUT command with PREEMPT service action action is used to: a) preempt (i.e., replace) the persistent reservation and remove registrations; or b) remove registrations. Change-Id: I906b09057e5ddef0ea2fe180bb5fff6e9e0a04f6 Signed-off-by: Changpeng Liu <changpeng.liu@intel.com> Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/436092 Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com> Reviewed-by: Jim Harris <james.r.harris@intel.com> Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>