NFSv4: Remove duplicate lookups, capability probes and fsinfo calls

When crossing into a new filesystem, the NFSv4 client will look up the
new directory, and then call nfs4_server_capabilities() as well as
nfs4_do_fsinfo() at least twice.

This patch removes the duplicate calls, and reduces the initial lookup
to retrieve just a minimal set of attributes.

Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>