knfsd: nfsd: allow auth_sys nlm on rpcsec_gss exports

knfsd: nfsd: allow auth_sys nlm on rpcsec_gss exports

Our clients (like other clients, as far as I know) use only auth_sys for nlm,
even when using rpcsec_gss for the main nfs operations.

Administrators that want to deny non-kerberos-authenticated locking requests
will need to turn off NFS protocol versions less than 4....

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>