NFS: Do not display the setting of the "intr" mount option

The "intr" mount option has been deprecated for a while, but
/proc/mounts continues to display "nointr" whether "intr" or "nointr"
has been specified for a mount point.

Since these options do not have any effect, simply do not display
them.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>