migration: Refactor repeated call of yank_unregister_instance

In the function qmp_migrate(), yank_unregister_instance() gets called
twice which isn't required. Hence, refactoring it so that it gets called
during the local_error cleanup.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Tejus GK <tejus.gk@nutanix.com>
Message-ID: <20230621130940.178659-3-tejus.gk@nutanix.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

migration/migration.c

@@ -1676,15 +1676,11 @@ void qmp_migrate(const char *uri, bool has_blk, bool blk,
     } else if (strstart(uri, "fd:", &p)) {
         fd_start_outgoing_migration(s, p, &local_err);
     } else {
-        if (!(has_resume && resume)) {
-            yank_unregister_instance(MIGRATION_YANK_INSTANCE);
-        }
         error_setg(&local_err, QERR_INVALID_PARAMETER_VALUE, "uri",
                    "a valid migration protocol");
         migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
                           MIGRATION_STATUS_FAILED);
         block_cleanup_parameters();
-        return;
     }
 
     if (local_err) {