pr-manager-helper: fix memory leak on event

Reported by Coverity.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scsi/pr-manager-helper.c

@@ -46,6 +46,7 @@ static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr)
     if (id) {
         qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc,
                                                   &error_abort);
+        g_free(id);
     }
 }