NFS: Ignore transport protocol when detecting server trunking

Detect server trunking across transport protocols. Otherwise, an
RDMA mount and a TCP mount of the same server will end up with
separate nfs_clients using the same clientid4.

Reported-by: Dai Ngo <dai.ngo@oracle.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>