migration: Minor control flow simplification

No need to declare a temporary variable.

Suggested-by: Juan Quintela <quintela@redhat.com>
Fixes: 1df36e8c6289 ("migration: Handle block device inactivation failures better")
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 5d39f44)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

migration/migration.c

@@ -3436,18 +3436,17 @@ static void migration_completion(MigrationState *s)
         ret = global_state_store();
 
         if (!ret) {
-            bool inactivate = !migrate_colo_enabled();
             ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
             trace_migration_completion_vm_stop(ret);
             if (ret >= 0) {
                 ret = migration_maybe_pause(s, &current_active_state,
                                             MIGRATION_STATUS_DEVICE);
             }
             if (ret >= 0) {
-                s->block_inactive = inactivate;
+                s->block_inactive = !migrate_colo_enabled();
                 qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);
                 ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false,
-                                                         inactivate);
+                                                         s->block_inactive);
             }
         }
         qemu_mutex_unlock_iothread();