migration/rdma: Fix rdma_addrinfo res leaks

rdma_freeaddrinfo() is the reverse operation of rdma_getaddrinfo()

Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210525080552.28259-2-lizhijian@cn.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>