NFSv4: Use the correct net namespace in nfs4_update_server

We need to use the same net namespace that was used to resolve
the hostname and sockaddr arguments.

Fixes: 32e62b7c3ef09 (NFS: Add nfs4_update_server)
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --cc fs/nfs/internal.h
Simple merge

diff --cc fs/nfs/nfs4client.c
Simple merge

diff --cc fs/nfs/nfs4namespace.c
Simple merge