md-cluster: make sure the node do not receive it's own msg

During the past test, the node occasionally received the msg which is
sent from itself, this case should not happen in theory, but it is
better to avoid it in case something wrong happened.

Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>