nfsd: Do not exempt NFSv3 Fsinfo from the TLS check

The Fsinfo RPC is exempt from the check for
Kerberized NFS being required, as recommended
by RFC2623. However, there is no reason to
exempt Fsinfo from the requirement to use TLS.

This patch fixes the code so that the exemption
only applies to Kerberized NFS and not
NFS-over-TLS.

This only affects NFS-over-TLS for an NFSv3
mount when it is required, but the client does
not do so.

(cherry picked from commit 3fc3fe90915f02e25b4f1d5070e8e01e465e873d)