Sync both unicast and multicast lists instead of unicast twice.

Fixes: cfc80d9a ("net: Introduce net_failover driver")
Reviewed-by: NJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>